Working with the IC-R75 and IC-R20 – Handy Radio Software

One of the perks of owning an IC-R75 “conventional” HF and IC-R20 handheld wide-band communications receivers is the ability for computer control. By connecting the RS-232 serial port on the rear of the IC-R75 to the computer, or the headphone/CI-V port on the IC-R20 to a CI-V level converter and then to the computer, software running on the computer can take control of the frequency and mode of the receiver.

My favourite software for performing computer control is Ham Radio Deluxe. Don’t let the name fool you – this software is perfectly capable of commanding radios for ham transmission or otherwise and gives you a virtually unlimited memory capability with banking, click-to-tune and mouse-wheel tuning, as well as a scanning spectrogram and record ability (you need to connect radio to the sound card). It supports various radios from Icom, Yaesu and others – so give it a go! For example, here’s my slightly-customized front-end for my IC-R75 – definitely beats futzing around with the front panel to key in frequencies or live with its 101 memory bank size.


While Ham Radio Deluxe was free software, the new Version 6 is now a paid for product. It’s probably best to grab Version 5 while you still can. But be warned, there are always bugs in it – so back up your settings inside %appdata% periodically, otherwise you might lose your memories and be in for a bit of pain. I had this once – and the backup files are in a different format necessitating a kludgy fix which I wrote. Please don’t judge my C – it was a quick and dirty fix … especially when no-one else was able to step up to the plate with a solution.

So, while tuning around the air-waves you will come across MANY different transmissions, many in digital, which can be decoded if you have a computer with a sound card. What follows is a non-exhaustive list of free (and non-free) Windows based software which I find handy to decode various radio modes and analyse signals. I have purposely not included software requiring special hardware or extreme expense (some software from Hokka and Klingenfuss are really for intelligence agencies, costing $8,000+). Keep in mind that while several pieces of software can decode the same modes – they don’t necessarily decode them with equal ability! Also, some of these programs run much better in Windows XP than they do on Windows 7.

Mostly useful for LF/MF/HF

Spectrum Lab

Spectrum Lab

Hands down, the first piece of software I will need when it comes to decoding transmissions is Spectrum Lab. This handy piece of software is useful to visualize what you are hearing (remember FFT?) as well as calibrate sound cards, align radios and perform decoding of several different data-modes (presets for FSK/DGPS modes) using the integrated digimode terminal. It also visualizes Hellschreiber modes and QRSS slow morse.



This one claims to do it all, and it does. But some modes (say HFDL, RTTY, DGPS especially) are better implemented by other programs. But if you only have one program, this one might just be it. When using the modes on the left, with some functionality disabled, the software is freeware which makes it quite nice – and when paid for, you can also use the modes on the right, otherwise they are restricted to five minutes use only. The software is my favourite for receiving radiofax – while the automatic reception mode is quite hit-and-miss and alignment of the frequency offset of the soundcard is touchy, the software produces much better imagery than most competing decoders that I have tried. The program also comes with a software called Clock which allows you to align your system clock to a radio clock, but I haven’t tried it. Note to people with multiple monitors/large screens – the program may crash on startup, so just launch with one monitor active and you’ll be fine. I have this problem since I have 2 x 1680×1050 monitors connected to a Matrox Dualhead2go which makes it a virtual 3360×1050 display and that crashes the program every time!

Digital Master


Digital Master, formerly Digital Master 780 is bundled in with Ham Radio Deluxe (in v5 and earlier, free) – it is a very well made decoder for Ham Radio Digital Modes such as RTTY, PSK31/63/125, QPSK31/63/125, Olivia, DominoEx, Hell, MT63, Contestia, RTTY-M, Throb and Thor. It also features multiple channel reception with a supersweeper mode which allows you to receive, in parallel, multiple BPSK-31 transmissions within the AF frequency window. With a very deep integration time, it’s also extremely sensitive (but slow) with Olivia modes which do the magic of recovering signals below the noise floor.



A worthy free contender is Fldigi, also available under Linux, is a highly featured multi-mode radio decoder as well. This one is also extremely capable for receiving wefax transmissions, and unlike MultiPSK, APT unattended reception is workable! I quite like it, but it does take a bit of menu-rifling to find the right mode and options …



Credit where credit’s due – JE3HHT Makoto Mori writes brilliant software. This is the first of my recommendations from him. This first software, as you can gather by its name, decodes slow-scan television (aka analog imagery) over radio supporting the widest set of modes I’ve seen with slant correction that can be adjusted during and after reception! Best of all, it’s free!


Radio amateurs have “modernized” their SSTV sending with digital modes based on the Digital Radio Mondiale OFDM encoding, squashed to fit within SSB bandwidths. EasyPal is the most reliable digital SSTV software I have come across, supporting bad block reports, repair transmissions, and adjustable compression – but it can be a bit slow. Digital modes work great when there is a signal lock, but due to the digital cliff, if you have less than about 10dB SNR, you are unlikely to see a single picture decode successfully. If it doesn’t work, I was going to recommend DigiTRX, but that seems to have disappeared.


Another hit from JE3HHT – this is the best RTTY decoder I’ve used, hands down. The configurable demodulation modes make great work of pulling text out of very muddy faded signals – highly recommended. Works where MultiPSK has no idea what’s going on … but you do have to be persistent in rifling through the settings to optimize your decoding. Fantastic adjustable squelch too. Also free!


Those with interest in military modes such as STANAG4285 and XSL really need something different from the above, and Sigmira pretty much fits the bill there. Also free, but picky about the computer you run it on and the OS – I’ve had better success with XP on this one.


Those interested in coded weak signal work, such as beacons, should look into WSJT transmissions. In fact, with the Weak Signals Propagation Reporter project (WSPR), a worldwide map of propagation is being built all the time in realtime!



This is a software for decoding DRM (Digital Radio Mondiale) transmissions on HF. These are basically “digital” radio over shortwave, most transmissions require 10Khz bandwidth so either a modified 12khz IF from a conventional receiver, or a SDR is required. Linked is the page with a pre-compiled Windows installer – it is controversial due to patent and licensing requirements for AAC/AAC+ decoders and so may be considered illegal in certain countries where such patents exist.

IZ8BLY Hellschreiber

Not that often used, but still, a useful mode to have which encodes graphics as either tone-bursts, FSK or in multiple tones, thus relying on the reader to interpret the graphic as text (i.e. human error correction). I prefer this software to the others for transmitting and receiving – it is simple and easy to use but still versatile.



Unfortunately, this software is no longer maintained by the looks of it, but it’s the best HFDL decoder I have met. Unfortunately, this is paid-for software, but the free alternatives pale in decoding quality. Without a license, you can probably get five-minutes decoding before it closes down, which is good if you want to identify the airport in the squitter messages, but even a check of the frequency table should be able to identify it. HFDL (high-frequency data link) is a mode used by aircraft to transmit basic flight data when out of range of VHF and not wanting to use expensive satcoms equipment.



The first of a series of useful software from COAA, also paid-for software, this allows you to perform boxcar integration on signals and “dig up” NDBs from below the noise floor and as a bonus, it will even decode the morse code for you! A unique and novel software for the DXer.



The second is BeaconSee which allows you to monitor the IARU beacons over time and display it as a chart so you know what the propagation conditions are actually like. Also paid-for, but is relatively unique for Windows. Has the ability to steer the radio over the serial port to allow for unattended operation and monitoring of all bands!



This is a nifty program that uses the ITS HF Propagation models developed by VOA to predict the signal quality at a given time between two points at a variety of frequencies. It makes VOACap usable for the average Joe.


I haven’t needed to use this, but it’s a data mode performed in software running on sound cards that is shaping up to be the replacement for expensive proprietary PACTOR modems in ship-to-shore e-mail communications. May come in useful, if it lets you monitor the transmissions (which I’m not sure it does).


Another fairly obscure radio mode which I’ve heard maybe only once or twice, also operating on sound cards providing digital keyboard to keyboard chat over HF SSB channels with fairly high sensitivity.

Mostly useful for VHF/UHF


This software is by far the best ACARS decoder I have used, very sensitive and reliable. Development seems to have stalled, and unfortunately, it does not run correctly under Windows 7, and needs XP. ACARS is a mode used by aircraft over land to perform low-speed data link activities for monitoring systems operations – in Australia, the primary ACARS frequency is 131.550Mhz in AM (as all aviation transmissions are), although there are secondary frequencies close-by.


A very good radio trunking system control-channel decoder which allows you to follow Motorola 3600bd, 9600bd, EDACS, P25 and MPT1327 trunking control channels and “steer” an appropriate receiver to follow the conversations on a trunked radio system. For example, when the GRN was using Motorola Analog Voice trunking with a digital 3600bd control channel, I used one radio fixed on the control channel to provide data to Unitrunker, which then steered my IC-R20 to follow the frequencies utilized by a talkgroup for a conversations. It is by design that trunking systems allocate frequencies almost-randomly so monitoring is difficult without a digital scanner (pricey) or two scanners, one of which is PC controllable.

Digital Speech Decoder

Ever since spectrum started becoming limited, deployment of digital voice radios became more common-place. Hobbyists with analog scanners really don’t have much to listen to nowadays as radios have transitioned to P25, TETRA or DMR (MotoTRBO) standards. This software allows you to “bring back some of the fun” – if you route the discriminator audio (and have a very good signal), then out of your sound card comes the decoded digital voice. Unfortunately, this will not undo encryption – so listening to encrypted services is an impossibility. Further to this, there are also patent issues with the software implementing AMBE/IMBE vocoders and so the software may be illegal.


This is a sound-card TNC allowing you to monitor and participate in packet radio networks – supporting 300bd for HF as well as 1200bd AFSK and 9600bd GMSK for VHF/UHF operation. The basic TNC itself is free, but some of the utilities which can go with it are paid-for.


APRS software allowing you to plot as well transmit and share APRS data. APRS is an AX.25 based packet system used by radio amateurs to communicate local-area information by radio including positional reports for tracking, and weather station reports. Free for those with a valid amateur radio callsign and license. Those who just want to view what the APRS map looks like can see on the website. How cool!


The best APT decoder software for those who want to receive APT images from NOAA satellites. This one seems to sync up the best, but the IC-R20 isn’t really sensitive on WFM, and clips quite nastily on regular NFM mode.

Mostly useful for SDR

HDSDR + ExtIO Plugin for RTL2832 TV dongles, or FCDs

HDSDR is my preferred SDR software. When coupled with the ExtIO plugin (from Balint Seeber, who I worked with and helped debug), you can use RTL2832 USB TV Tuner dongles as a ~2-3Mhz bandwidth SDR with about 8-bit resolution. An SDR on the cheap – a search of the internet gives you many many hits about this, so I won’t go on about it too much but it definitely works. Or you could use the Fun-Cube Dongle. Alternatives you can use include Winrad, but WRplus (formerly my favourite as it had proper WFM Stereo decoding) has “time bombed” and the author is now authoring commercial software only.

Spectravue + FCD

A fairly basic alternative SDR software which can be used with the Fun Cube Dongle for some narrow-bandwidth SDR fun.


Now when someone says to me – “how much software do you need?” – the answer is obvious. Lots of it. When you get into a hobby, you start to amass piles of software which tackle very specific jobs. The choices for Linux of course, are different – and sometimes are much better (e.g. GNU Radio), but don’t offer the same user friendliness. There are more pieces of software which could come in handy, but I just haven’t found them or needed them … yet …

About lui_gough

I'm a bit of a nut for electronics, computing, photography, radio, satellite and other technical hobbies. Click for more about me!
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2 Responses to Working with the IC-R75 and IC-R20 – Handy Radio Software

  1. stephen thomas says:

    thanks for the info. great page.

  2. Dani says:

    Thanks for this great page! I’m recently owning an Icom IC-R20 as my first shy approach to the radio world and soon I will acquire a CI-V cable (RS-232 to 2x 3,5mm jacks) and it will be soon very usefull. Greetings from Barcelona!! //*//

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