Tagged: HF

Spyverter Sneak Preview

The Spyverter is being developed by the creators of the Airspy software defined radio to be a high performance upconverter. It is designed for use with the Airspy, but may also be compatible with other SDR devices too.

Compared to most other upconverters which use a diode ring mixer architecture, the Spyverter uses a different, as of yet undisclosed architecture. The main claimed advantages over other upconverters will be it’s low loss and high IIP3 performance, which means that the Spyverter will not saturate in the presence of strong signals as easily as other upconverters.

Recently a photo of a Spyverter alpha board was released, indicating that the Spyverter is getting close to release.

The Spyverter Alpha
The Spyverter Alpha

Also, a few months ago W9RAN posted a YouTube video about a prototype HF upconverter for the Airspy and we believe he was using an early version of the Spyverter.

Airspy HF Converter Sneak Peek by W9RAN

Receiving Hellschreiber with the RTL-SDR and an Upconverter

Over on YouTube user BSoD Badgers has uploaded a video showing reception of Hellschreiber on HF at 20m. To receive the HF frequencies he used a ham-it-up upconverter. He used SDR# to receive the signal and the Fldigi decoding software to decode the signal.

Hellschreiber is a fax-like communications mode used by amateur radio hobbyists.

Receiving BPSK63 with an RTL-SDR and Ham-It-Up Upconverter

Over on YouTube user Java’s Toys has uploaded a video showing a demo of his reception of a BPSK63 signal using his RTL-SDR and the Ham-it-up upconverter. BPSK63 is a text based digital communications mode used by ham radio enthusiasts to make contacts. It is twice as fast compared to the more commonly used BPSK31 mode.

Java’s toys used HDSDR together with Fldigi to receive and decode the signal.

Understanding Filtering in an Upconverter for the RTL-SDR

Over on YouTube user w2aew has uploaded a video tutorial explaining how filtering in an upconverter works. In a previous video w2aew explained how a simple upconverter for the RTL-SDR worked and noted that for best performance the upconverter needs three filters, one preselector at the input, one after the local oscillator and one after the mixing stage.

In this video w2aew takes a Nooelec Ham-it-up upconverter which has the three filters mentioned above implemented and scopes the output after each filter to show their effect on an input signal.

#175: Filter functions in an HF Upconverter used with RTL-SDR Dongle Receiver

Using a Mixer to Listen to HF on a RTL-SDR Dongle

Over on YouTube user w2aew has uploaded a tutorial video that clearly explains the theory behind upconverters. Upconverters are commonly used with the RTL-SDR to receive the HF (0 – 30 MHz) bands. In the video he shows how to make a simple homemade double-balanced diode ring mixer for the RTL-SDR and shows its performance in HDSDR.

#174: Using a mixer to listen to HF, shortwave, ham, etc. on RTL-SDR dongle

New Experimental R820T RTL-SDR Driver that Tunes down to 13 MHz or Lower

Over on the Osmocom mailing list, Oliver Jowett an RTL-SDR experimenter has posted about his new experimental driver for the R820T RTL-SDR which extends the tunable range down to around 13 and up to 1864 MHz (previously 24 – 1766 MHz). Oliver writes

You can get these changes from https://github.com/mutability/rtl-sdr/ (you’ll need to build from source yourself). There should be no application changes needed, just tune as normal. (gqrx needs the “no limits” option turned on) These changes work by limiting the tuner to a range of frequencies that it can reliably tune to, then allowing tuning beyond those bounds by making the 2832’s downconverter do the final bit of tuning. This can add up to 14.4MHz to each end of the range. Also, the tuner is switched to low-side mixing at the top of the range which gives a bit more range there. The practical range is limited by the width of the IF filter and aliasing effects at the extreme edges of the downconverter’s range. I’ve been able to pick up broadcast AM and amateur CW/SSB down to around 15.5MHz without too much trouble. I’d be interested to know how this works for others. Also.. these changes are likely to have broken offset tuning, direct sampling mods, and tuners other than the R820T, as it touches all those areas but I only have an unmodified R820T to test against. If you have different hardware and are willing to spend some time testing then please let me know. I expect that the range of the other tuners can be extended in the same way with not much trouble.

Over on the Reddit RTL-SDR discussion board there has been talk about this patch. Most users are reporting that it works well down to around 15 MHz, but some people are reporting that they have been able to receive signals down to around 4 MHz. Testers also report that this modified driver works much better than the no-hardware direct sampling mod patch released a few months ago.

Update: A ready to go Windows binary for SDR#can be downloaded at https://mega.nz/#!K0YwyLDb!jMdJb2DwjMTnyDFZ-mda5mQfcu464gB945eQnOJj82g. Simply copy the file in the zip into the SDR# folder.

Reddit user gat3way was able to take this screenshot showing AM reception at 9.5 MHz
Reddit user gat3way took this screenshot showing AM reception at 9.5 MHz

New Japanese HF Upconverter for the RTL-SDR

A new HF upconverter designed for the RTL-SDR has gone up on ttrftech’s Japanese language blog (use Google Translate). The upconverter is called the ‘SC-HFCONV-100’ and comes with 100 MHz oscillator, SMA connectors, USB mini-B power.

Currently the upconverter is only available for sale on the Japanese Amazon store, but it is possible to still order it through the jzool-agent Japanese shopping service.

Japanese HF Upconverter
Japanese HF Upconverter

RTL-SDR Easy HF Dongle Mod

Over on YouTube user crookedninja5 has uploaded a video showing what he calls the “Easy HF dongle mod”. The mod involves soldering a wire from Pin 1 on the RTL2832U chip to the static protection diode near the antenna input. At the same time he also uses the modified RTL-SDR dll file for SDR# which enables the “no hardware mod” direct sampling mode.

Using this mod he is able to get decent coverage of 0 – 14.4 MHz.

SDR Shortwave Radio Mod "easy HF dongle mod"