Category: FT8

Reverse Beacon Network (RBN) Real-Time Azimuthmal Map

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A new release of RBN Aggregator now supports FT8 in addition to the traditional modes. It was installed at this location as seen below:

G0LUJ RBN Aggregator 5.1, monitoring 8 bands

Given the large volumes of textual data, interpretation of the monitoring results was difficult – what was needed was a real-time graphical solution that could easily provide a general overview of propagation conditions based on the data.

HA8TKS, with credit to an idea by CT1BOH, has implemented such a solution which I have found to be very useful. It defaults to the last 15 minutes of RBN data from the spotter that is selected and auto-updates. Observing the path lines on the globe over a few minutes gives one a very quick indication of conditions at that spotter’s location. I have added a link to the website top menu.

Map of RBN Spotter G0LUJ

Categories: CW, FT8, RBN, Uncategorized

HF Noise Reduction, VHF Sporadic-E

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The reactivation of the KiwiSDRs from the home location revealed a noisy spectrum with weak signals, and pronounced vDSL interference.

vDSL Interference 8.5-12 MHz

The spectrum was not a surprise, and was the reason why I initiated a remote antenna project last year. Now that the remote location is no longer available, it was evident that I would have to make the best of it from the home location.

Using lessons learned from remote antenna project, the following actions were performed:

1) The 8 port Ethernet switch, which was plastic, was replaced for one with a metal case. The switch was then moved 20m away from the receivers (and antenna) and the receivers were connected to the switch with CAT6 shielded Ethernet cable.

2) All power supplies were assessed. It was found that the non-switch mode supply powering the Wellbrook antenna had gone faulty and was producing birdies across HF. It was replaced.

3) After reading about how domestic telephone extension cables can re-radiate vDSL signals, the telephone extensions (which are unused) were disconnected at the master socket.

4) The Wellbrook ALA100LN antenna was moved further away from the property, with the head unit raised to a level of 2m above the ground.

5) The Medium Wave (MW) bandstop was re-inserted into the system to improve non-MW weak signal reception by reducing overload.

The overall result was an improvement and tests against known signals, such as RAF Volmet, demonstrate that it is now adequate for general reception, and probably as good as could reasonably be expected from a suburban location.

The recent Sporadic-E openings provided an opportunity to assess the KiwiSDR noise floor and reception by examining the 10m CW beacon band. The frequency labeling of the beacons took about 2 hours, spread over a couple of days:


10m CW Beacons


I will add the 10m CW beacon monitor to the website when I have configured it.

6m FT8 has been very busy. I have concentrated on the receive setup for optimisation. Highlights below:


Ukraine on 6m CW


PZ5RA on 6m FT8


XE2JS received on 6m FT8

Monitoring of 4m has resumed.


Categories: 10m, 4m, 6m, CW, FT8, HF, KiwiSDR, LF, VHF, WSPR

Preparing for the Sporadic-E season

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Having proved an interesting experiment, the 2m/70 cm SDRPlay antenna was removed to prepare for the arrival of the Sporadic-E season on VHF.


The flowchart below indicates the new signal processing arrangement:

Except for brief periods of transmission, the intention is to continuously monitor a range of frequencies and modes on the 50, 70 and 144 MHz bands simultaneously in the hope of capturing short-duration propagation enhancements. This to run concurrently with the existing monitoring from the Wellbrook Loop which covers from 2200-10m.



MSK144 24/7 coverage of 6m, 4m and 2m.


WSPR 24/7 coverage of 2200, 630,160,80,60,40,30,20,17,15,12,10,6,4,2m
FT8 24/7 coverage of 6m,4m,2m and 8 lower bands (MF/HF) dependent on day/night.
CW coverage shadows the 8 FT8 MF/HF bands.
Other modes on an ad-hoc basis, such as Opera, contingent on spare CPU capacity.


144.360 MHz MSK144, EB1HRW QRB 1349 km


144.174 MHz FT8, DC2TH QRB 1104 km
144.4285 MHz JT65b, GB3VHF reception QRB 357 km
144.174 MHz FT8, Sunday afternoon
The 50 and 70 MHz monitor PC, showing MSK144 activity
SDR Console V3 on Core I5 PC (Mode names added to picture)


I tried to hear G3ZJO on 2m Opera. I did not succeed, but he decoded me:
Eddie, G3ZJO, receiving my Opera signal on 2m QRB 221 km
Categories: CW, FT8, JT65, MSK144, Opera, SDRPlay, WSPR

SDRPlay feedpoint receiver project for 2m/70cm

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After removing all equipment from the remote site and re-assembling what could be accommodated at home, it became evident that I had some spare items which could form the basis of a new project.

Recent discussions with Bri, G0MJI, regarding UHF operating generated interest in developing an antenna project using a receiver as close to the feed point as possible to minimise feed losses, something that could be useful at 70cm and above.

The USB extension cable from an SDR could take the place of a coax run, which would also be cost beneficial as low loss coax has become increasingly expensive. If successful, the concept could be applied in future to the 23 cm band where it could yield greater benefits.

The equipment comprised of the following, most of which I already had available:


Assembling parts
Testing SDR fit inside the enclosure
Completed, ready for installation
Installed in temporary position
The USB cable was connected to a remote computer, and SDR Server (V3) was used to send data over the network to be viewed by SDR Console V3.
Tests were conducted with satellite downlink signals and terrestrial FT8 on the 70cm band:
CW Ident of VZLUSAT1 (QB50 CZ02)
 NBFM voice on SAUDISAT-1c (SO50)


G0MJI (IO83NI) transmitting FT8 (Distance: 47 km)
The project concluded successfully, with qualifications. The SDRPlay RSP1 does not have a TCXO, so there will be challenges in the UHF range. This could be mitigated by replacing the RSP1 with the RSP1A which has a 0.5 ppm TCXO.  The satellite signals were weak but usable – both passes were of low elevation – a good preamp would probably improve things markedly.
Overall, the ability to independently tune around the 2m/70cm bands with an SDR is a very useful additional capability installed at next to no cost.


Categories: FT8, Satellites, SDRPlay