Kieran Sullivan I remembered seeing this a couple of days ago.
Don't know if they would be stable enough for your measurements, specs included below George Shaiffer http://www.mpja.com/Frequency-Meter-8Digit-100KHz-24Ghz-Red/productinfo/34279+TE/ [Frequency Meter. 8Digit. 100KHz-2.4Ghz]<http://www.mpja.com/Frequency-Meter-8Digit-100KHz-24Ghz/productinfo/34112+TE/> [http://www.mpja.com/images/5note.gif] Frequency Meter. 8Digit. 100KHz-2.4Ghz<http://www.mpja.com/Frequency-Meter-8Digit-100KHz-24Ghz/productinfo/34112+TE/> Item #: 34112 TE $18.95 [Frequency Meter. 8Digit. 100KHz-2.4Ghz Green]<http://www.mpja.com/Frequency-Meter-8Digit-100KHz-24Ghz-Green/productinfo/34280+TE/> [http://www.mpja.com/images/clear.gif] Frequency Meter. 8Digit. 100KHz-2.4Ghz Green<http://www.mpja.com/Frequency-Meter-8Digit-100KHz-24Ghz-Green/productinfo/34280+TE/> Item #: 34280 TE $18.95 [Frequency Meter. 8Digit. 100KHz-2.4Ghz Red]<http://www.mpja.com/Frequency-Meter-8Digit-100KHz-24Ghz-Red/productinfo/34279+TE/> [http://www.mpja.com/images/clear.gif] Frequency Meter. 8Digit. 100KHz-2.4Ghz Red<http://www.mpja.com/Frequency-Meter-8Digit-100KHz-24Ghz-Red/productinfo/34279+TE/> Item #: 34279 TE $18.95 PLJ-8LED is a cost-effective microprocessor based, eight-digit digital frequency display. It can be used for conventional frequency measurement. Features: small size and reliable performance. Settings are automatically saved Features: Processor: Microchip PIC16F648A Power: 9V ~ 15VDC (with reverse polarity protection ) Operating current up to 160 mA Eight 0.56in. High brightness Red LED Display 8 Display Brightness settings (factory set to the highest) Zero auto blanking, 2.5ppm Voltage Controlled TCXO Frequency reference Unique gate control & accurate time algorithm (non-timed interrupt mode). Multi Gate time: 0.01 seconds 0.1 seconds 1.0 seconds Measurement Input: High impedance Three Measurement modes (Low, High & Automatic) Low Frequency Mode Range: 0.1 MHz ~ 60 MHz Accuracy: ± 100Hz (0.01sec. Gate) ± 10Hz (0.1 sec. Gate) ± 1Hz (1.0 sec. Gate) Sensitivity: 1 MHz to 60 MHz: better than 60 mVPP High Frequency Mode Range: 20 MHz to 2.4 GHz Accuracy: ± 6400 Hz (0.01sec. Gate) ± 640Hz (0.1sec. Gate) ± 64Hz (1.0 sec. Gate) Sensitivity : 20 MHz ~ 30 MHz: Better than 100mVPP 30 MHz ~ 60 MHz: Better than 50mVPP 60 MHz ~ 2.4GHz: Not tested Auto Mode Automatically selects the High or Low Mode according to the input signal frequency, The crossover frequency is 60 MHz. Connections: DC IN: HX2.54-2P socket RF IN: HX2.54-2P socket ICSP: (programming interface) 2.54-6P pin L: 4-7/8” W: 1” H: 7/8” WT: .12 ________________________________ From: altusmetrum <altusmetrum-boun...@lists.gag.com> on behalf of Kieran Sullivan <narei...@googlemail.com> Sent: Sunday, August 12, 2018 12:14 PM To: Bdale Garbee Cc: Altus Metrum Subject: Re: [altusmetrum] Which gplEDA tools? Thanks. I think my main issue is the lack of accurate frequency counter. I had hoped to get close with an SDR radio receiver as my o’scope doesn’t quite manage 435Mhz with a great deal of accuracy. The frequency I measured and calibrated to at least got me to the point that the tele-dongle flashed red when receiving packets, but obviously there was a problem with the reception/checksum so nothing valid received. I will get this cracked and I do know someone with a spectrum analyser/frequency counter that I can get hold of, just a matter of doing this. Good to know about the bring-up script too, I think I missed that. Regards, Kieran > On 10 Aug 2018, at 19:59, Bdale Garbee <bd...@gag.com> wrote: > > Kieran Sullivan <narei...@googlemail.com> writes: > >> Oh, and when someone figures out a good way to calibrate the radio on >> the Telemega, please let me know. I’ve been trying to get it right for >> a couple of years on and off… :-) > > Oh, sorry, I thought we had the process documented but apparently in > manual section 11.8.2 we basically just tell you not to do this > yourself. We should probably add a new appendix to the manual > explaining how to do it with suitable caveats about "don't try this > unless you have the right gear and know what you're doing, or are really > desperate". > > In the meantime, if you want to cal a board, you need some way to > accurately measure frequency near 435 Mhz (Keith and I both have > high-end frequency counters locked to GPS disciplined reference > oscillators on our benches). Once you have that, there are two ways you > could go: > > First, the ao-bringup/turnon_telemega script in the ao-bringup > subdirectory of our fw/altos repo is our current production script. The > relevant bit is that it calls cal-freq with a device argument and the > SERIAL environment variable set to the board serial number to do the > frequency cal. > > The other option is to do it all by hand. Connect to the board over USB > with a terminal program, and the 'c s' command will show you the > currently configured frequency and PLL calibration factor. Use the 'C' > command to generate a steady carrier, measure the actual frequency the > board is transmitting on, and then you can calculate an updated cal > value using the equation: > > <desired frequency> / <measured frequency> * <current cal value> > > Use 'c f' to set that new cal factor, and 'c w' to write the updated > value to flash. Then use the 'C' command to confirm the board is now > transmitting on the desired frequency. > > Hope that helps! > > Bdale _______________________________________________ altusmetrum mailing list altusmetrum@lists.gag.com http://lists.gag.com/mailman/listinfo/altusmetrum
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