472kHz WSPR analysis by PA1B

Bert, PA1B, has done some analysis of my 472kHz WSPR to see how little power (ERP) would be needed to be still copied. Of course, this assumes reception is not external noise limited.

10m WSPR DX analysis by PA1B

Bert PA1B has done some analysis of my recent 10m WSPR spots in Paraguay. At times, much lower power than my 500mW would probably have been enough to be spotted by ZP4KFX.

6m WSPR analysis by PA1B

Bert PA1B has done some analysis of my recent aircraft scatter WSPR spots on 6m.

As is usually the case, clicking the image will bring up a larger chart.

PA1B's analysis on my 6m WSPR spots

Hello Roger,
At the moment I am very busy with all sort of things.
I am making a new website in Wordpress, which is taking a lot of time.
We did some house improvement, for about two more weeks.
And today we went to the opening of the outdoor swimming pool with my grand children.
(great fun)
This evening I took some time to make an analysis of a number of spots on 6 meter.
I took the most interesting spots for airplane scatter.
I hope you like it and can place it in your blog.
I left in M0EMM to show the difference. hi
Positive drift means the path is becoming shorter.
It's my pleasure.

73, Bert PA1B

Hello Roger,

The spots of M0MVB shows spots where the path is becoming shorter (+3Hz per minute)
and spots where the path is becoming longer.   (-2 Hz per minute)

I just saw that the spots of M0YOU with scatter, are much stronger than the spot without scatter.  The lower the lowest possible power, the stronger the signal.  A lowest possible power of 1 mW is 17 dB stronger than 50 mW. hi.

I left in the spots of M0EMM, to show that there is no Doppler andthe signals are not that strong.

Good luck in further analysis,

73, Bert PA1B

10m WSPR analysis by Bert PA1B

Bert PA1B has analysed my 500mW WSPR spots today, ignoring the many spots by local G4IKZ.   It shows the signal strengths (uV/m) implied by the S/N figures.  In many cases, much lower powers would have been enough to get "spotted".  Thank you Bert.  Of course, for some people, the noise floor limits the minimum signal that can be detected.

UPDATE 2200z:  The last USA spot of my 500mW was WG2Z (5600km) at 1724z. Just local G4IKZ (18km) since then.  Now QRT on 10m until after breakfast, but will stay on 472kHz overnight.

PY2RN WSPR analysis

Bert PA1B has analysed my recent reception on WSPR by PY2RN to see just how little power could have been used and still be successfully decoded in Brazil - the answer is very little for a lot of the time! Most times even 1mW should have been enough. This of course assumes local noise levels allow decoding to the lowest levels for WSPR at around -30dB S/N. In some cases this may not be possible because of local QRN/QRM.

Six continents on 10m WSPR

This afternoon I exchanged WSPR reports with RI1ANF in the South Shetland Is in Antarctica on 10m. This now means I've had reports this year from every continent on the 10m band using 5W or less with the wire halo antenna.

PA1B's power attenuator calculator (see link below)

As this is all getting rather too easy (!) maybe I need to follow Bert PA1B's advice and build a switchable attenuator so I can repeat the challenge with much lower powers. See his power attenuator design page for details of how to make suitable RF attenuators to reduce QRP rig output powers to milliwatts.

PA1B's QRPp website

Bert PA1B has an excellent website describing his experiments with very low power on HF. Using his FT817 with various simple attenuators he has been able to work some remarkable DX with powers ranging from 1mW to 500mW. His website explains how he has achieved this. It is an inspiring page showing just what is possible.

PA1B analyses my 137kHz WSPR results

Bert PA1B has done some interesting "reverse analysis" of the WSPR reports I've given people. Working back from these you can estimate the lowest levels (in mW) that they could have used and still been copyable with me. This also gives a good guide to the likelihood of these stations receiving my weak signal. It is clear that M0BMU should be able to copy my 50uW ERP signal frequently (which he does) but that I'd need a lot more ERP to be able to get reports from the PA stations or SM6BHZ. See attached table from Bert.

PA1B's QRPp website

Whilst looking at the links on PC4T's blog I noticed Bert PA1B's excellent website all about QRPp operating with lots of tips on how to produce mW power levels and have real fun on the HF bands.

This has encouraged me to have a go, so I am currently WSPR beaconing on various HF bands using 10mW out from the FT817 via a 20dB attenuator right next to the rig.These were the results from 40m late this afternoon and into the early evening. Encouraging!

Best DX 983km with 10mW in just a few hours!