WSPR Dreamcatcher Doc instructions

I followed the WSPR doc instructions on my orange Pi PC2 running Armbian.

I plugged in a RTL-SDR.com version 3 dongle and attached the antenna connection to my 3 foot high 8 Wire Discone antenna.

10 minutes later I was picking up a WSPR signal from Alice Springs Australia. Like 3000 km away from Philipines.

I was stunned. But I checked on the WSPR net website and there was the confirming line on the map stretching from Australia to Philippines.

My question is does these instructions which allow for Q mode (basically a underclocking of the dongle) only apply to the generation 3 RTL-SDR dongle with a TXCO crystal or can I use a $9 Blue rtl dongle from China and use the PPM correction (-52 in my case) to correct the frequency.

you can calibrate a cheap rtlsdr dvb-t dongle too for wspr reception, but it’s 20 ppm xtal will get de-tuned time to time as ambient temperature varies…

the RTL-SDR V3 dongle a good choise as has a precise TCXO on board and wspr is very sensitive for that.

hint: you can transmit wspr too, but that’s works only on Raspberry Pi SoCs: http://www.rtl-sdr.com/pitx-qrp-tx-shiled-for-wspr-on-20m-now-for-sale/

Thanks for the reply Zoltan.

I ordered a WSPR hat for my rapberry two weeks ago so hopefully it will arive in a couple of weeks.

I am so looking forward to transmitting WSPR.

I am temped to try with just some wire onto the Raspberry Pi.

I know it is a square wave but I have heard people are getting out.

I am stunned by how well wspr receives. I just picked up a SPOT from Vladivostok.

I was thinking that the WIDE option in WSPRD might help deal with this.

not sure what WIDE option do exactly but the fact WSPR has about 6 Hz bandwidth while 4 FSK make the thing very clear that high precision is needed.

also it’s very sensitive to short term variations (like when warm air column is moving around the xtal and dragging the frequency up and down) This is why OCXO is common on higher bands.
https://www.qrp-labs.com/ocxokit.html

By the way, QRP-Labs:
there are some amateur groups, using small WSPR transmiter on pico balloons, transmit the positions (locator), not on 14 MHz, but on 10.138 MHz.
I think, it is ouf of the rage of the Rafael Micro,s r820t tuner based rtl-sdr.
One group is in Melbourne Australia, based on Andy,s VK3YT not-public transmitter construction.
Last flight was PS-70 in end of jan, in the middle of australian summertime.
Its call was VK3YT-11 on aprs, maybe can access its telemetry on aprs.fi:
https://aprs.fi/#!call=a%2FVK3YT-11&timerange=3600&tail=3600
Another active group is around QRP-Labs, and they uses the Labs open transmitter constructions.
The last flight was on the ukhas map some days ago, around north Canada, its callsign is S-25:
https://tracker.habhub.org/#!mt=roadmap&mz=3&qm=3_days&f=S-25
All the flights connected to QRP-Labs listed here:
https://www.qrp-labs.com/flights.html
t.janos

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Re RTL Dongles running WSPRD this is from the WSPRD authors GITHUB account.

I think this answers my own question as I have been unable to get the blue generic Chinese RTL dongles to work with WSPRD.

“WARNING – Crystal stability
Most of RTL dongles use a cheap crystal, and frequency drift can avoid WSPR decoding. The use of no-name RTL dongle for VHF/UHF bands usually require crystal modification, for a better one. External clock could be also used, like GPSDO or rubidium reference clock, aligned on 28.8MHz. In some case, it’s possible to use the factory crystal (usually HC49, through hole), using a good thermal isolation. I successfully used two device with no modification, but it’s tricky, easy to miss the window, and RTL devices does not allows fine frequency tuning. For now, a good option is to buy a RTL device designed for SDR applications and integrating a 0.5ppm TCXO. After many tests, I would recommend this version : NooElec NESDR SMArt - Premium RTL-SDR w/ Aluminum Enclosure, 0.5PPM TCXO https://www.nooelec.com/store/nesdr-smart.html”

I have ordered a Nooelec SNArt dongle from Amazon.

that would be a better choice probably it has nice HF circutry inside