RNEI Radiogram

There will be a demonstration RNEI Radiogram broadcast using EasyDRF on February 3 (UTC), from WRMI Florida.

The details are:

Frequency	Date	Time
5850kHz	February 3rd	0100 UTC
7780kHz	February 3rd	0100 UTC
15770kHz	February 3rd	1300 UTC

EasyDRF is the only program that can decode this broadcast. Make sure you have the latest version. Download it HERE.

📖 RNEI Radiogram Program preview 📖

Program introduction
QAM4, RS4 – HTML page
QAM4, RS3 – Image 1 (SVG Weather chart)
QAM4, RS3 – Image 2
QAM4, RS3 – Image 3
QAM16, RS3 – Image 4
QAM64, RS4 – Image 5
QAM64, RS4 – Image 6
Program end Program duration: 30 minutes.
RNEI Radiogram is followed by the 2nd half of RNEI25 – including Mamma’s Mest Metal and Stephen’s segment.

Setting up

It’s a good idea to record the broadcast in case something goes wrong during live decoding. An IQ recording is the most flexible, as it allows later demodulation in DSB, ISB, SSB or AM.

Best demodulation performance is probably DSB (AM Sync/locked carrier), followed by SSB then lastly normal AM (envelope detection). An ISB recording (SAS on the KiwiSDRs) allows either sideband to be selected later. NR and SDR# Antifading must NOT be used on the data.

This show will start with an HTML page sent using robust QAM4 mode and RS4 error correction, followed by image files that will start at QAM4 RS3, then increase to QAM16 RS3 and finally QAM64 RS4. The page will automatically load the image files for display. The higher QAM mode image files require a better quality signal to decode.

As soon as the HTML file saves, click the “RxFiles” button to open the folder where the received files are saved, then drag the HTML file into your web browser and it will open.

The images will automatically display in the page as they are decoded and saved, but this will take place gradually as the program progresses over about 30 minutes. Links are also provided, to allow the original images to be viewed in full quality via the internet.

EasyDRF will save SNR data into a Javascript file, which the HTML page will also automatically load and display. This allows easy gathering of stats on the reception quality that listeners are experiencing.

Feeding audio into EasyDRF

Make sure you have the most direct audio input from your radio to EasyDRF.

If you are using an SDR, a virtual audio cable (like VB HiFi Audio Cable) is probably the best choice.

If you are using a physical radio, using an audio cable into your “line in” port is usually the best option. However, some computers are noisy and a direct connection can degrade reception. If this happens, the audio input can be RF isolated using RFC filtering, ferrites or an audio transformer. A last resort is to use a microphone placed in front of the radio speaker. This will be sensitive to room noises, and also means the data will be audible throughout the broadcast.

Ensure audio levels are adequate, but not in overload. QAM64 in particular is very sensitive to distortion.

Summary

• EasyDRF is required to decode the broadcast – Available HERE. (Be sure to use the latest version).
• EasyDRF is Windows software. EasyDRF can run under Wine in Linux, and possibly also under Winebottler on Mac (unconfirmed).
• Recording the broadcast is wise, in case of decoding problems. IQ recordings are recommended.
• Best demodulation performance is probably DSB (AM Sync/locked carrier), followed by SSB then lastly normal AM (envelope detection).
• ISB AM Sync can also be used from a recording, and allows either sideband to be selected later.
• Avoid using SDR# “Antifading”, as this destroys the data quality. Use DSB mode with “Lock carrier” set ON and NR OFF.
• EasyDRF now features a DC blocker on the audio input to allow it to work with the KiwiSDRs in AM Sync modes.
• The HTML file will be sent first (best viewed on a widescreen monitor).
• When the HTML file saves, click “RxFiles” to open the folder, then drag and drop the HTML file into your web browser.
• Once the HTML file is displayed, it will automatically display the image files as they arrive.
• SNR stats will also display in real-time on the top right corner of the HTML page.

– Daz