Category: Amateur Radio

Using a direct sampling enabled Airspy as a Panadapter for a Yaesu FTDX-5000

Tim Havens is an avid CW operator on the ham bands and primarily uses his Yaesu FTDX-5000 transceiver for this purpose. At the same time he also uses a software defined radio coupled with an upconverter as a panadapter by connecting the SDR to the 9 MHz IF output of the Yaesu.

However a problem Tim encountered was that the frequency drift of any SDR he tried was too large, even with a TCXO based software defined radio (like a modded RTL-SDR or the Airspy), and that it was a constant hassle to recalibrate. Furthermore, he noticed that the upconverters he used introduced their own drift which just added to the overall frequency drift.

To get around this Tim decided to use the Airspy in a special configuration. First he used the external clock input of the Airspy to connect to his Jackson Labs “Fury” GPSDO. This device uses GPS satellites to generate a very accurate 10 MHz clock, with almost zero drift. Secondly, to get around the need for an upconverter with it’s own frequency drift he used the ADC1 direct sampling input ports on the Airspy to connect to the 9MHz IF output of his FTDX-5000 through an extra band pass filter and LNA.

Tim writes that he will soon update his post with more images and a video.

Airspy with external GPS clock and ADC1 output connected.
Airspy with external GPS clock and ADC1 output connected.

Transmitting DATV DVB-S Video with the HackRF Blue

Simon (G0FCU) has been using his HackRF Blue to transmit DVB-S video captured from his video camcorder. In the ham radio hobby there is something called digital amateur television (DATV) in which amateurs transmit digital video over radio to repeaters. Simon writes that in the UK DATV is usually transmitted at above 1.2 GHz and in the DVB-S format, which is the same format used by some satellite TV services.

Although there are dedicated DATV radios, Simon decided that he wanted to use the HackRF Blue as the radio for transmitting his own DATV signals. To do this he uses the software dvgrab to grab the video stream from the camera, then passes it to ffmpeg to compress the raw video into MPEG-2 and then uses a GNU Radio program called gr-dvbs to use the HackRF to transmit the DVB-S stream at 1000 MHz.

To test that his signal was transmitting correctly, Simon then used a standard DVB-S satellite TV with the LNB bypassed. 

Previously we also posted about using a BladeRF for transmitting DATV DVB-T signals.

What the DVB-S output signal looks like on another HackRF.
What the DATV DVB-S output signal looks like on another HackRF.

A Review of the TitanSDR Pro

Over on the swling.com blog, Thomas has uploaded a review of the TitanSDR Pro that was published in the May 2015 version of The Spectrum Monitor online magazine. Although the TitanSDR pro software defined radio is an expensive (1,380 EUR for the basic / 1,970 EUR for the PRO), it may be of interest to those looking to go further into the short wave listening hobby. The TitanSDR is a high performance 9 kHz to 32 MHz receiver with 16 built in preselectors and a bandwidth up to 2.1875 MHz. It’s main markets appear to be government intelligence and military, but it also finds good use in general short wave listening.

Thomas reviews the TitanSDR positively, liking its easy to use software and its superb sensitivity, but noting that it’s high price may be a bit off putting.

Also, in the current June version of The Spectrum Monitor magazine Thomas also reviews the SDRPlay, a $149 USD HF capable radio, also giving it a favourable review.

The TitanSDR Pro
The TitanSDR Pro

Review of Nobu’s HF Upconverter, Galvanic Isolator and 14 MHz Low Pass Filter

Back in April we posted about some new products made by Japanese RTL-SDR experimenter and product manufacturer Nobu. Nobu’s new products were a 1:1 galvanic isolator and a low pass filter. The galvanic isolator isolates the antenna from the RTL-SDR and PC, significantly reducing noise. The low pass filter is useful when used with direct sampling modified RTL-SDRs to filter out any strong interfering signals that are above 14 MHz.

Recently Nobu sent us at RTL-SDR.com some samples of his products. He sent us one of his HF upconverters, a galvanic isolator and a low pass filter.

NobuProducts
Nobu’s RTL-SDR Products: HF Upconverter, Galvanic Isolator, Low Pass Filter. Placed next to an RTL-SDR for size comparison.

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Listening to a Radio Amateur Stratosphere Balloon with an RTL-SDR

Over on YouTube user kpappa has uploaded a video showing his reception of the J43VHF radio amateur stratosphere balloon with an RTL-SDR dongle and discone antenna. On the 10th of May radio amateurs in Greece launched a high altitude balloon. The balloon carried a transceiver payload which allowed amateurs to talk to each other via the balloon at a frequency of 144.200 MHz. The video shows good reception of the balloon and also shows it’s tracking via APRS.fi.

More information about the balloon can be found at https://j43vhf.wordpress.com/ and http://hellashab.blogspot.gr/.

The high altitude balloon's radio payload recovered after landing.
The high altitude balloon’s radio payload recovered after landing.
Tracking J43VHF (Radio Amateur Stratosphere Balloon) by RTL-SDR & Diamond Discone D3000N Antenna

A 1961 Drake 2B Receiver using an RTL-SDR as a Panadapter

The Drake 2B is an old analogue tube based radio from 1961. Although it is so old it is still considered a decent shortwave receiver. Over on YouTube user M0HBR decided to bring his Drake into the modern age by coupling it with a panadapter made from an RTL-SDR dongle. A panadapter is a device that allows you to view the RF spectrum and waterfall of a normal radio. 

To do this he tapped into the 455 kHz IF output of the Drake and amplified it with a homebrew FET source-follower, before connecting it to the RTL-SDR. He then uses the HDSDR software to listen to and display the received signals on the waterfall.

Drake Dongle Derring-Do -- 2B Goes SDR

Sigimira Decoder now supports the RTL-SDR Directly

Sigmira is a popular free Windows software program which supports decoding of radio modes such as PSK31, RTTY, CW, STANAG 4285, Japanese Slot Machine, FSK, HFDL and M141 as well as standard modes such as NFM, AM, USB and LSB.

Previously Sigmira could be used with the RTL-SDR by piping audio into it from another program such as SDR#. In the latest version that was just released Sigmira now directly supports connecting to the RTL-SDR, allowing for a spectrographic display and point and click tuning. Sigmira also now includes a database with frequencies of over 2000 known signals.

Screenshot of the Sigmira decoding software which now supports the RTL-SDR directly.
Screenshot of the Sigmira decoding software which now supports the RTL-SDR directly.
Sigmira Signal Database
Sigmira Signal Database.

How to Setup CWSkimmer with an RTL-SDR and HDSDR

Over on YouTube user Brent Crier has uploaded a tutorial video showing how to set up CWSkimmer with an RTL-SDR and HDSDR. CWSkimmer is regarded as one of the best pieces of software that can be used to decode CW a.k.a Morse code.

Morse code is a communications technique still used widely by the amateur radio community in the HF bands. The RTL-SDR can receive HF frequencies and Morse code with an upconverter or direct sampling modification.

In the video Brent goes over the installation of HDSDR, Virtual Audio Cable, and a program called Virtual Serial Port (VSP) manager as well as the needed settings for each program. The set up he shows allows CWSkimmer to automatically change the frequency in HDSDR when tuning in CWSkimmer.

How to setup a CWSkimmer with a RTL SDR and HDSDR