Pretty Excellent Receiver for Software-Eager Unperceivable SignalsSDR Receiver for VLF-LF-HFPERSEUS is a VLF-LF-HF receiver made by is based on a outstanding direct sampling digital architecture. It features a 14 bit 80 Ms/s analog-to-digital converter with an exceptional 76 dB SNR (BW = 40 MHz), an high-performance configurable FPGA digital down-converter with an up to 1 MS/s output sampling rate and a 480 MBit/s, high-speed USB 2.0 PC interface. Unlike in lower class direct sampling receivers, the PERSEUS RF analog front-end has been carefully designed for the most demanding users and includes a 0-30 dB, 10 dB steps attenuator, a low-loss 10 bands pass-band RF preselector filters bank, and an high dynamic preamplifier with a top-class input third-order Intercept Point of more than 30 dBm. The resulting third-order dynamic range is 103 dB for SSB signals (2.4 KHz BW) and 107 dB for CW signals (500 Hz BW).PERSEUS is a so-called software-defined receiver.

CODE300-32 PSK Analysis (1) Pubblicato da aNdReA a 03:45. Etichette: Code300-32, PSK, signal snalysis. Schema a blocchi di ricevitore SDR progettato e testato in ambiente GNU Radio Companion. Allo scopo ho utilizzato una chiavetta USB DVB-T. Segnale orario RAI / FSK 33 Bd.

This means central properties of reception, demodulation, use and usability are all controlled by the software. One example for this would be filters protecting the signal from interference. In place of just a few filters, each for only a specific narrow bandwidth, as has been standard so far, now the software itself filters the reception signal. This allows listeners to tailor bandwidth exactly to each interference condition, modulation and operating mode with no further need for purchasing additional filters or sacrificing reception quality during filter selection.But what makes PERSEUS truly revolutionary is a real-time frequency display capable of spanning a spectrum of up to 1600 kHz.

By clicking on individual stations within this spectrum, they can be selected for listening in unprecedented quality.Whats more, the entire frequency spectrum can be saved to hard drive. In effect, this permits listening to anything within that spectrum of up to 400 kHz later on. On top of this, it is also possible to further adjust the spectrum after recording.

PERSEUS is capable of displaying the full spectrum from 10 KHz to 40 MHz with a resolution bandwidth of 10 kHz and a dynamic and spectral purity comparable to the best spectrum analyzers available on the market. That function PERSEUS was developed special software for Windows, HFSPAN, given that came with your receiver.Software HFSPANinternal viewfront panelrear panelPERSEUS is a SDR receiver and use PC software to make the process of demodulation. The compatibility and support of application software most used by radio amateurs are provided by a DLL library for the Microsoft Windows operating systems.Available now the new version of with the full control and integration of PERSEUSPERSEUS package include:. Perseus receiver. USB cable.

power supply 110/220V. driver for Windows. PERSEUS Software. HFSPAN Software. DLL for WINRAD. user manual on PDF. Warrenty 2 years - compile with CE Mark.

Table of Contents.IntroductionA software-defined radio is a radio implemented with reconfigurable software,which processes the raw samples of a digitized radio signal. This differs fromconventional hardware radios, which employ RF circuits and digital signalprocessors to implement this processing in a way that is hardwired andhardcoded to their application.Software-defined radios offer the allure of instant reconfigurability in everydimension: frequency, modulation, and protocol. In theory, you would simply runa different program to implement an entirely different radio — whether it’s aFM broadcast receiver, a UMTS handset, or a Bluetooth device. While there arestill real-world limitations to this dream, particularly in antennas and inhost processing power, software-defined radio today is a powerful technologyfor building flexible communication systems, exploring the radio frequencyspectrum, and for protocol research and development.

How It WorksA software-defined radio still requires some hardware, but this hardware isrelegated to just receiving and transmitting radio signals. In total, asoftware-defined radio system consists of an antenna, a transmitter and/orreceiver, and a host computer.When receiving, the antenna converts electromagnetic waves into a voltagesignal, which is then amplified, translated down from the tuning frequency, andsampled by an SDR receiver. The digital samples are streamed to the host forprocessing.When transmitting, the host streams digital samples to an SDR transmitter,which converts them into a voltage signal and translates it to the tuningfrequency. The voltage signal may then be further amplified by an externalamplifier and filtered by a transmit filter, before it is radiated by theantenna as electromagnetic waves.Conventional hardware radios today increasingly resemble software-definedradios internally, as more of their processing is pushed into the digitaldomain, and more complex protocols demand integrated CPUs. However, they arestill tightly integrated black boxes that are designed to operate on a specificfrequency band, whereas software-defined radios provide a raw sample interfaceand tend to have a wide tuning range.

Current StateSoftware-defined radio has become increasingly accessible over the past yearswith the commoditization of high performance CPUs, and the availability of lowcost, high rate analog to digital converters (ADCs) and digital to analogconverters (DACs) that are responsible for sampling and synthesizing the radiosignal. The inexpensive $20 RTL-SDR dongle — described in more detail below —has also played a role in exposing the technology to many engineers andhobbyists.However, the software of software-defined radio has yet to catch up to thehardware. Much of it is scattered across esoteric one-off decoding programs,trapped in frameworks bloated with boilerplate and dependencies, or confined toproprietary Windows software. There has been little consolidation of commoncode by the way of libraries, and even less effort on good documentation.Fortunately, the tide seems to be turning.

Lightweight signal processinglibraries are gaining traction, modern open source SDR applications arecropping up, and the developer communities surrounding SDR are growing.The rest of this guide covers the details of getting started with SDRreceivers, including hardware, software, a tour of the frequency bands, nextsteps, and additional resources. Most of this introduction focuses on SDRreceivers, but SDR transmitters are touched on briefly in the next stepssection. Hardware Basic SpecificationsA software-defined radio receiver is defined by three basic specifications:bandwidth, resolution, and tuning range. The receiver is further characterizedby many important figures of merit that reflect performance in noise,selectivity, and frequency stability, but these specifications are deferred tomore advanced discussions.Bandwidth is the instantaneous width of frequency content that the SDR receivercan receive. It can be thought of as the width of the SDR’s window into the RFspectrum.

This is usually in the range of 1 to 10 MHz for entry-level SDRreceivers, and in the 20 to 60 MHz range for the more advanced SDRtransceivers. Bandwidth is different from tuning frequency; rather, morebandwidth means that the SDR receiver can capture a wider window of signalssimultaneously when tuned to a particular frequency. In some cases, morebandwidth is required to capture a very wide signal, like a 6 MHz widechannel.The sample rate of an SDR receiver is the rate the radio signal is sampled bythe receiver and streamed to the host.

Sample rate is directly related to thebandwidth, and while bandwidth is ultimately the specification of interest,SDRs are typically described by their sample rate, as it is the underlyingdesign parameter. An SDR’s effective bandwidth is usually slightly less thanits sample rate. Sample rate also dictates the computational burden on thehost: the wider the receive bandwidth, the more samples per second are requiredto represent it, and consequently, the more bus throughput is required tostream it to the host, and the more host computational power is required toprocess it.Resolution is the bit resolution of the analog to digital converter thatsamples the radio signal. This represents the quantization range of eachsample.

For example, an 8-bit ADC will have 256 levels of quantization,whereas as 12-bit ADC will have 4096 levels. All things equal, more bitresolution means less quantization noise — the “noise” resulting from the errorin mapping an analog level onto a discrete level, and more dynamic range — theability to capture both strong and weak signals simultaneously. In practice,the usable resolution is highly dependent on the signal conditioning by thefrontend RF circuitry.Tuning range is the frequency range that the SDR receiver can tune to. RTL-SDR Blog Silver Dongle NooElec Blue Dongle AntennasPerhaps the most “software-undefined” component of software-defined radio isthe antenna.

It is also one of most important. Good reception on a particularfrequency band primarily depends on the antenna configuration. Antennas varyin design frequency, bandwidth, directionality, and polarization, and differentapplications demand different requirements in these properties.An antenna’s physical size is typically proportional to the wavelengths it isdesigned to receive. For example, antennas designed for reception at 15 MHztend to be much larger than those designed for 100 MHz, and especially largerthan a WiFi antenna designed for 2.4 GHz.

Stock antenna, includedwith some RTL-SDR dongles. For example, the small stock monopole antenna that comes with some RTL-SDRdongles (often the generic ones) is limited in performance and frequencyresponse to higher UHF frequencies. Users may be disappointed when they are notable to pick up much aside from some UHF signals and very strong FM stations.But this is entirely to be expected for an antenna of its design and size,especially when used indoors and at a low elevation.Wideband antennas, or antennas that can receive a broad range of frequencies,are popular with SDRs, as they can accommodate the wide tuning range of theSDR. For example, theis a common wideband antenna design. However, to get the most performance outof any dedicated antenna, it should be placed outdoors and at high elevation. RTL-SDR BlogDongle+Antenna KitFor getting started with SDR, without initially investing too much time, money,or real estate for an antenna, the RTL-SDR Blog’s is probably the all-around best entry levelkit.

The included tall 1.5m telescopic antenna performs decently for VHFsignals, even when used indoors, and the shorter 20cm telescopic antenna coversmuch of the UHF band, so these two antennas can adjusted to most of theoperating range of the RTL-SDR. All of the VHF LuaRadio examples (WBFM, NBFM,AX.25, POCSAG, RDS) can be run with the tall 1.5m telescopic antenna indoors. SoftwareSome of the earliest SDR software has its origins in the late 90s, with dial-up(e.g. The U.S.Robotics “WinModem”) that implemented the majority of the modem in software,allowing for more inexpensive hardware. Other early SDR software was softwaresupport for amateur radio digital modes (FSK, PSK31, PACTOR, AX.25, etc.) thatwere modulated in the audio band. Amateur radio operators could interface theaudio of their radio transceivers to their PC’s sound card, and use software toreceive or transmit these digital modes.Sound card operated digital modes are still popular in the amateur radiocommunity today, and there is an abundance of older decoding software from thisera in use or under maintenance. Some of this software has been retrofitted tosupport modern I/Q sampling SDR receivers like the RTL-SDR.Today, SDR software seems to broadly fall under five categories: waterfallreceivers, standalone decoders, frameworks, libraries, and web interfaces.Below is a Linux-biased sampling of active SDR software projects.

Waterfall ReceiversWaterfall receivers are characterized by a real-time vertical, showing the frequencyspectrum of the SDR receiver’s passband over time. Waterfall receivers alsosimulate many functions of a wideband hardware RF receiver, like tuning,demodulation modes, filters, and listening to demodulated audio. Waterfallreceivers are useful for exploring the RF spectrum and selectively demodulatingparts of it. Waterfall in.

(for offline use).Standalone DecodersStandalone decoders are applications written to specifically decode one or moredigital modulations and protocols, like aircrafttransmissions, pager messages,etc. and many more.LibrariesLibraries provide digital signal processing routines, without imposing aparticular paradigm on their integration. They are a lightweight alternative toframeworks.

(also a standalone tool)FrameworksFrameworks offer a suite of operations and an API to flexibly define customreceivers, transmitters, or signal processing in general. These are useful forrapidly prototyping SDR projects, but may also be integrated into standaloneapplications.Web InterfacesWeb interfaces provide a browser frontend to an SDR, often with server-sideprocessing for demodulation and decoding, and a client-side waterfall andaudio. They are like a waterfall receiver accessible through a browser.Radio BandsThe radio spectrum is split up contiguously into named regions called bands.Each band refers to a range of frequencies. Several international standardshave demarcated and named the radio spectrum bands, but in this introductionwe’ll stick to the, e.g.

HF, VHF,UHF, etc.Radio spectrum bands are not a pure commodity; a slice of the HF band is notequivalent to a slice of the VHF band. This is because electromagnetic waves ofdifferent radio frequencies have different interactions with the atmosphere andearth, and this affects their propagation. Propagation on certain bands may besensitive to time of day, space weather, and solar weather. Propagation onother radio bands may depend mostly on line of sight, and may only be sensitiveto terrestrial weather. The atmosphere may also present more or less opacityfor different frequencies to outer space, depending on the radio band.

Ineffect, the various radio bands offer varying locality, which enables differentkinds of communication.The bandwidth for each ITU band is not divided equally, but ratherlogarithmically. Each subsequent band has approximately ten times the bandwidthof the previous. This turns out to be a useful assignment, because thefrequencies within many of these bands have roughly similar propagationcharacteristics. However, this also means that each frequency band —characterized by a mode of propagation — offers different amounts of spectrumcompared to other frequency bands.For example, 802.11b WiFi operates around 2.4 GHz in the UHF band (300 MHz to 3GHz).

A single 802.11b WiFi channel is 22 MHz wide, which amounts to only 0.8%of the UHF band, but on the HF band (3 to 30 MHz), that single channel wouldrequire more than 80% of the entire band — not to mention the propagationrelated reasons that this would be a bad idea.The amount of spectrum available in a band dictates the bandwidth of signalsyou can fit in the band, especially if the band is shared among multiple users.For digital signals, this also dictates the maximum achievable data rate (see). This isone reason that high data rate wireless technologies today occupy spectrum inbands up in the gigahertz.Below is a tour of the more common ITU frequency bands, including their primarymode of propagation and what kind of signals can be found on them. Thesedescriptions are by no means complete; spectrum allocation is complicated andregion dependent.

Snapshot of U.S. Spectrum Allocation for LFThe (LF)spans from 30 kHz to 300 kHz. Signals on LF primary propagate by propagation.Due to limited spectrum in this band, LF is home mainly to low data ratedigital signals. In particular,which “atomic” clocks synchronize their time to (likeat 60 kHz), and used fornavigation. In the past, the upper half of the band carried 9 kHz wideamplitude modulated audio broadcasting in some regions, and a few stations are,but this has largely been phased out over the years and replaced withbroadcasting on MF or VHF.There are also some region-dependent amateur radio allocations. Snapshot of U.S. Spectrum Allocation for MFThe(MF) spans from 300 kHz to 3000 kHz.

Signals on MF propagate by both andpropagation, but the lowertwo-thirds of the band typically only propagate well by skywave at night.The lower portion of the band, up to 500 kHz, is used for, like in LF.Nearly half of the band, from 520 kHz to 1600 kHz, is dedicated to 9 kHzwide amplitude modulated audio broadcasting, commonly called.Above AM radio, there is an international amateur radio allocation from 1800kHz to 2000 kHz, named the. This band is the start ofamateur radio privileges in many countries. Amateur radio is discussed in moredetail in the Amateur Radio section under Next Steps.Broadcasting begins again at 3000 kHz and up. However, the aforementioned 160meter amateur radio band and this broadcasting band are colloquially lumpedinto HF, in part because their propagation mode is inclined to skywavepropagation, and frequencies from 1600 kHz to 30 MHz were historically called.

These allocationswill be covered in the next section.Otherwise, MF carries assorted region-dependent emergency communications insome of the open patches between 1600 kHz to 3000 kHz.Since AM radio station signals in the MF band are capable of propagating byskywave under the right conditions, there is a hobby called for the long distance reception(“DXing”) of AM radio stations across state or nation boundaries. Snapshot of U.S. Spectrum Allocation for HFThe (HF)spans from 3 MHz (3000 kHz) to 30 MHz. Signals on HF propagate primarily bypropagation, in which signalsskip between the Earth and the ionosphere, enabling them to travelinternational and transoceanic distances. However, this propagation issensitive to space and solar weather conditions, as those phenomena affect theionosphere.If the radio spectrum is an ocean, then the HF band is its coral reefs.Crowded and full of diverse international life, the HF band — commonly calledshortwave — is a global meeting point on the radio spectrum.

With radio, thiselectromagnetic conduit and natural wonder forms an infrastructure that enablesworldwide communication.Shortwave is well known for its international radio broadcasts, whoseallocations arethe HF band. Shortwave radio stations typically broadcast 10 kHz wide amplitudemodulated audio.

Many stations are government-run, providing news, culture, andpropaganda to domestic and international audiences. These stations oftenbroadcast in several languages, and may use directional antennas to targettheir transmissions towards particular regions, e.g. The Voice of AmericaAfrica service.

Some government-run stations are public service stations, likethe time stations, and, which broadcast continuously withvoice announcements of the time, or digital marine weather and news stations,which may use protocols likeorto carry text and images,modulated in the audioband of 3 kHz widemodulated transmissions.Although shortwave broadcasting is dominated by government-sponsored stations,private shortwave broadcasting exists too. In the US, much of it is religious,with a few stations that carry music and talk programs.

For a complete scheduleof shortwave radio stations, check out.The HF band is home to many international,where amateurs can carry out morse, voice, or digital communication with oneanother. Voice modes are usually 3 kHz wide single-sideband modulated audio.Digital modes are typically modulated in the audioband within thesesingle-sideband audio transmissions. Morse code uses a modulation method called, which isessentially ancarrier. HF amateur radio operators often participate into make the most contactsin a limited period of time.The military has a presence on HF as well, often for air force and navy relatedcommunications. Some governments have run at some point in timeto deliver instructions to the military or agents operating on foreign soil.Several numbers stations continue to operate to this day. Many number stationsuse ordinary amplitude modulated broadcasts that can be received by anyshortwave radio.HF is also used as backup commercial aviation and maritime communication.Aircraft on trans-oceanic flights are required to be equipped with an HFtransceiver.

The international maritime distress and calling frequency is.A notable allocation towards the upper end of the HF band at 27 MHz is. Thisallocation provides a, allowing localunlicensed communication for individuals.

CB radio uses 10 kHz wide narrowbandfrequency modulated audio, rather than the amplitude modulation that is commonthroughout the HF band. Snapshot of U.S. Spectrum Allocation for VHFThe (VHF) spans from 30MHz to 300 MHz. Signals on VHF propagate primarily by, similarto light.

However, VHF radio waves experience a slightly farther horizon thanvisible light, called the radio horizon, due to refraction in the atmospherefor these frequencies. VHF radio waves can penetrate non-metallic objects likedrywalls, although with attenuation, and can reflect off of large metallicobjects like buildings.Approximately a quarter of the VHF band is dedicated to audio and televisionbroadcasting. The common broadcasting sits at 87to 108 MHz, carrying 200 kHz wide frequency modulated audio.

Televisionbroadcasting allocations vary from region to region, but typically arecomprised of two contiguous bands in the 40 MHz to 80 MHz range, and one largeband in the 170 to 216 MHz range. Most television broadcasting has switched todigital, using the 5 to 8 MHz wideprotocol in much of the world, ortheprotocol in North America. Some regions have reallocated 174 to 230 MHz fromtelevision to digital audio broadcasting, with the 1500 kHz wideprotocol, in aneffort to eventually upgrade from analog FM radio.VHF has aviation and marine navigation and emergency communication allocations.(VOR)navigation beacons sit directly above FM radio broadcasting, at 108 to 118 MHz.The spans from 118 to 137 MHzfor air traffic control communication, and uses 10 kHz wide amplitudemodulation audio (in contrast to most frequency modulated audio signals onVHF). Uses 16 kHzwide frequency modulated audio in the 156 to 162 MHz range.

(AIS) isa position reporting system used by ships, located at the end of the Marine VHFband. AIS uses a 10 kHz wide digitalmodulation.Amateur radio typically has two main allocations on VHF, the from 50 to 54 MHz and the from 144 to 148 MHz.The 6 meter is a somewhat experimental band, exhibiting long distance skywaveandpropagation under certain seasonal and meteorological conditions. The 2 meterband is a very popular amateur radio band for voice communications, oftensupported by local thatreceive and rebroadcast transmissions from a high elevation for extendedreception, and used for amateur satellite.Amateur radio operation on VHF is typically 10 kHz wide frequency modulatedaudio, carrying voice or a digital protocol likefor packet radio, but can also be3 kHz wide single-sideband modulated audio, or even continuous wave for morse.The VHF band has numerous allocations for licensed business and public servicetwo-way radio communication. Many of these still use analog frequency modulatedaudio, but some carry digital protocols likeand may even bemultiplexed with a.In the US, unlicensed is also providedby the allocationfrom 151 to 154 MHz. Snapshot of U.S.

Spectrum Allocation for UHFThe (UHF) spans from 300 MHzto 3 GHz. Signals on UHF propagate primarily by, like in VHF.UHF is by far the most diverse band with respect to devices and digitalmodulations. Its short wavelengths allow for efficient, compact antennas, whichcan be easily integrated into portable electronics and small appliances, likemobile phones or WiFi routers. UHF is the primary spectral medium for cellularand wireless technologies today.Like VHF, UHF has some allocations for audio and television broadcasting.Television broadcasting spans from approximately 470 to 800 MHz, using thedigital 5 to 8 MHz wide protocolin much of the world, or theprotocol in North America.Audio broadcasting is also available in some regions in the 1452 to 1492 MHzband, with the 1500 kHz wide digitalprotocol.DAB/DAB+ is the leading standard in replacing analog FM broadcast radio in mostof the world.Approximately 20% of the UHF band is allocated for cellular technologies.

Theallocations vary by region, and depending on the carrier that owns the band,may carry different protocols, e.g. GSM (2G), UMTS (3G), or LTE (4G).Allocations tend to exist near 800 to 900 MHz and near 1700 to 2200 MHz bands.See the page onWikipedia for more information.An important set of international allocations are the (ISM) bands. Despite theircatch-all name, the vast majority of low power local wireless technologies,from garage door openers and weather sensors, to WiFi, Bluetooth, ZigBee, andNFC, all use these bands. The ISM bands were originally intended to isolatenoisy electromagnetic devices, like microwaves at 2.45 GHz or some medicaldevices, from clean spectrum reserved for communications. In effect, the ISMbands were unlicensed wild west zones in the spectrum and any devices designedfor it needed to be robust to incidental interference. Over time, low powerlocal wireless technologies have proliferated on these bands.The UHF band has two major ISM allocations. The lower frequency one ranges from433 to 435 MHz in ITU region 1 (e.g.

Europe, Africa, Middle East), or from902 to 928 MHz in ITU region 2 (e.g. Americas, Greenland). These bands areoften called 433 MHz or 915 MHz, respectively, and are frequently used for lowdata rate signaling devices, like key fobs or home alarm systems. These devicestypically use a simple digital or modulation.The higher frequency ISM allocation is from 2.4 to 2.5 GHz, which spans 100 MHzand is available worldwide. This allocation is frequently used by high datarate systems, like WiFi or Bluetooth, with more sophisticated digitalmodulations like,and.Amateur radio has several allocations on the UHF band, the most common of whichis thefrom 420 to 450 MHz. Like the 2 meter band on VHF, the 70 centimeter band isalso commonly used for voice communications, supported by localthat receive andrebroadcast transmissions from a high elevation for extended reception, andused for amateur satellite uplink. The UHF band also includes the, and the allocationsfor amateur radio, which might be used for experimental purposes or for amateurradio satellite uplinks.

Amateur radio operation on UHF is typically 10 kHzwide frequency modulated audio, but can also be 3 kHz wide single-sidebandmodulated audio, or even continuous wave for morse.The UHF band has several allocations forunlicensed two-way communications by individuals and businesses. For example,certain regions have aallocation from 476 to 478 MHz, similar to the HF Citizen Band. Much of theEU has the allocation from446.0 to 446.2 MHz, with channels set aside for analog 10 kHz wide frequencymodulated audio, as well as the digital 6.25 kHz wideand 12.5kHz wideprotocols. The US and some other countries in the Americas, have the (FRS) and(GMRS) inthe 462 to 467 MHz range. GMRS requires a license to operate in the UnitedStates.

FRS and GMRS use analog 10 kHz wide frequency modulated audio.Aircraft use a position reporting system calledwhich is centered at 1090 MHz (for “Mode-S” transmissions) in the UHF band. The1090 MHz Mode-S transmissions use a 50 kHz wide.Other notable allocations in the UHF band include those for satellitecommunications., andall useallocations inside of the 1 to 2 GHz range for their downlink, at carrierfrequencies around 1.2, 1.3, and 1.6 GHz. The, andsatellitetelecommunication services operate uplink and downlink in several bandsallocated across the 1.5 to 1.7 GHz range. Satellite radio services, like, have a 2310 to2360 MHz allocation for downlink in North America. These systems all usedigital modulations and custom protocols. SHF and beyond.

Snapshot of U.S. Spectrum Allocation for SHFThe (SHF) spans from 3GHz to 30 GHz. Signals on SHF propagate by, like inUHF and VHF, but due to their small wavelengths, SHF radio waves may also befocused by reasonably sized highly directional antennas, e.g.SHF has two allocations from 5.725 to 5.875GHz and 24 to 24.25 GHz. The 5.8 GHz is commonly known for its use in the Wi-Fi802.11a, 802.11n, and 802.11ac protocols. These protocols either useor digital modulations.Amateur radio has several allocations on the SHF band, including the 9, 5, 3,and 1.2 centimeter bands.

These bands are well suited for amateur radiosatellite communication, as well as experimental point-to-point communications.Due to the achievable high directivity and large spectral bandwidth available,SHF is commonly used in point-to-point links for terrestrial and spacecommunications. For terrestrial communications, these are often used intelecommunications backhaul, linking to theirnetwork. For satellite communications, the SHF band subsumes the more commonIEEE band names, and half of, many of which have allocationsdedicated to satellite communication and satellite television broadcasting.

Snapshot of U.S. Spectrum Allocation for EHFThe (EHF) spans from30 GHz to 300 GHz. Signals on EHF propagate by as well,but the higher frequencies have limited range due to atmospheric absorbance bywater and oxygen molecules. EHF signals are sensitive to.The EHF band is used for high data rate, short terrestrial point-to-pointlinks, as well as some satellite communications up to about 50 GHz.

Theatmosphere absorbs most EHF frequencies above this, rendering it unusable forsatellite communication — see the. Theprotocol isdesigned to operate around 60 GHz for local high data rate wirelesscommunication. Otherwise, much of the EHF band is undeveloped.The high data rate, and consequently wide bandwidth, signals on SHF and EHF arenot easy to receive, process, or transmit with off-the-shelf SDR transceivers,as their bandwidth is limited to up to about 60 MHz.

In general, SDR technologylags behind that of conventional hardware with respect to bandwidth, due tolimited efficiency of analog to digital conversion technology at very highsample rates, and the computational burden very high sample rates impose.The (THF) spans from 300GHz to 3 THz. Signals on THF propagate by.Technology to radiate and modulate THF radio waves is still in the researchphase, but this band will probably be limited in application to close rangehigh bandwidth point-to-point links (at least on Earth), like much of the EHFband. Next Steps Amateur RadioA great way to further develop radio fundamentals is to become an amateur radiooperator. Amateur radio is the hobby of making radio contacts, experimentingwith radio hardware and antennas, and for some, providing backup communicationsin case of an emergency that compromises local infrastructure.Portions throughout the RF spectrum have been set aside by internationalagreements expressly for amateur radio use. An amateur radio license grants theprivilege to transmit on these spectrum allocations, often with unrestrictedchoice of modulation and protocol, and at high power (e.g.

Up to 1.5 kilowattson many bands in the United States). Without an amateur radio license, legalradio transmissions with unlicensed hardware are limited to relatively lowpower on the crowded. A mapof the US amateur radio allocations is available.The spectrum dedicated to amateur radio would be worth billions if it were soldfor private ownership, so it’s a delicate blessing that politics have favoredthis culture in telecommunications history. As it stands today, transmittingwith a radio is not protected under a right like free speech, but is a licensedprivilege regulated by the government.Operating amateur radio helps to develop an intuition for real world signals,like the bandwidth of various analog and digital modulations, the propagationof different radio frequency bands, and the logistics of operating a legaltransmitter. It also revisits some recurring themes in technology, like thetrade-offs between analog vs. Digital systems, proprietary vs. Open standards,and centralized (VHF/UHF repeaters) vs.

Decentralized (HF) networks. Getting a LicenseIn the United States, amateur radio licenses come in three levels: TechnicianClass, General Class, and Extra Class.

The Technician license grants transmitprivileges on all amateur radio bands above 30 MHz, whereas the higher licenselevels grant transmit privileges on progressively more spectrum in the lowerfrequency HF band. The Technician license can be obtained by scoring 75% orbetter on a 35 question multiple choice exam, and costs about $15 to take.These tests are not difficult to pass, as the question and answer pools foreach level are published in advance.Studying for the amateur radio license is a great way to learn basic conceptsabout modulations, propagation, antennas, and international spectrum laws. Thisis the six-step plan I followed to getting a license and on the air in about1.5 weeks:.

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Find a local exam session with. Read book. Practice flash cards on or. Take and pass the exam. Wait until your call sign appears in the. Make your first contact on a local VHF or UHF repeater with a BaofengorCultureThe amateur radio culture in the United States is a peculiar mix of radiogeeks, electronics tinkerers, and preppers. Some enjoy it simply for casualconversation with like-minded radio enthusiasts on their commute to or fromwork.

Others are in it purely for the decentralized, self-sufficient means ofcommunications it enables, perhaps for survival preparedness or forvolunteering for emergency communications. And many hams tinker with antennas,low power transceivers, installing repeaters, or even building dedicated.Hams were some of the originalof their time, andthough on bad days may share their hand-wavy engineering, they also have ahistory of publishing academic-esque articles on subjects like propagation,circuits, and antenna design.

A is anomnidirectional antenna that looks like a disc on a cone. It has approximately10:1 bandwidth, relative to the center frequency. Which makes it a good choicefor the VHF and UHF bands as a receiving antenna.

A discone antenna with acenter frequency of 50, 75 or 100 MHz is reasonably sized, and can beconstructed with materials from your local hardware store.For receiving and transmitting on the 2m and 70cm amateur radio bands on VHF orUHF, an inexpensive option is the, which can be boughtassembled for about $25.Some applications require specific antennas for effective reception ortransmission, because of properties like long wave length, polarization, ordirectionality. For example, receiving a VLF time station benefits from aresonant magnetic loop antenna, which is substantially smaller in size than itsequivalently performing dipole or monopole electric field antenna. Receivingcircularly polarized radio waves from satellites, e.g.

A weather satellite,benefit from a circularly polarized antenna, like a quadrifilar helix antenna.Receiving the ISS, as it orbits the Earth at a certain elevation, is a loteasier with a directional Yagi antenna.Certain situations, like electrically noisy apartment buildings or the lack ofoutdoor access, may also call for alternate antennas designs like, which can producebetter results indoors than an electric field antenna. RF UpconverterIn order to receive the lower frequency LF, MF, and HF bands on the RTL-SDR,they must be translated into the tuning range of the RTL-SDR. This can be donewith the help of an inline RF device called an upconverter, which translate arange of frequencies up by a constant frequency offset.

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For example, a 125 MHzupconverter designed for the lower frequency bands will translate signals from0 to 30 MHz to 125 to 155 MHz.Two popular upconverters that can be used with the RTL-SDR and other SDRreceivers for the LF, MF, and HF bands are the and the. They are available for around $50 to$60 (with a shielded case).

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NooElec Ham It Up Airspy SpyverterAn appropriate low frequency antenna (e.g. Long-wire antenna) and one of theseupconverters enable an SDR receiver with a higher tuning range to receive thelower frequency bands. HardwareThere are several SDR receivers on the market with better performance andhigher sample rates than the RTL-SDR:.

— 3, 6, or 10 MSPS sample rate,24 to 1800 MHz tuning range, 12-bit ADC, $99 USD. — 2.5 or 10 MSPS sample rate, 24 to1800 MHz tuning range, 12-bit ADC, $169 USD. — 2 to 10.66 MSPS sample rate,100 kHZ to 2000 MHz tuning range, 12-bit ADC, $99 USD.

— 2 to 10.66 MSPS sample rate,10 kHz to 2000 MHz tuning range, 12-bit ADC, $169 USDThere are also many SDR transceivers on the market. Note that transmitting withan SDR with the intent of high power radiation (i.e.

Code 300-32 Sdr 10

Not testing locally orwith a loopback) requires some additional external hardware, like an RF poweramplifier and a transmit bandpass filter.