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My FSH4 doesn’t sync its internal frequency reference to GPS

Obar94 — Mon, 20 Apr 2026 02:55:24 GMT

Hello,

I’ve used my FSH4 spectrum analyzer (3.6 GHz version) for many years. I’ve found that while the supplied Garmin GPS accessory for the FSH4 allows it to access GPS satellite information, the FSH4 does not use it to synchronize its internal frequency reference with the information provided by the GPS signal (as verified using a second spectrum analyzer with its own GPS-locked external reference). Consequently, I’ve always had to use an external 10 MHz reference signal input to the FSH4's accessory BNC connector whenever I needed accurate frequency calibration with this instrument. Without doing this, the instrument internal frequency accuracy is only good for a little better than about 1 ppm.

This is strange, because the FSH4 manual states that the instrument is supposed to sync frequency with the GPS system when the antenna is connected, it is even supposed to remember the correction parameters for a day or so after the antenna is disconnected.

Could someone please assist me as to whether I may not have configured the instrument settings correctly? I am a retired electrical engineer.

Thank you for any suggestions!

Rohde and Schwarz RTO64 Probe calibration not working

HIYOTH — Wed, 19 Nov 2025 15:17:19 GMT

Daer Team,

I am trying to calibrate the probe of RTO64.But I am getting the below waveform.Could you please help me

Could you please help me.

RE: Rohde and Schwarz RTO64 Probe calibration not working

HIYOTH — Thu, 20 Nov 2025 10:01:44 GMT

Yes It was contact issue.I did not press the positive (black connector properly).After that the results are coming as expected please see the below image.

RE: Rohde and Schwarz RTO64 Probe calibration not working

Gough Lui — Wed, 19 Nov 2025 17:38:28 GMT

The screenshot appears to indicate DC coupling was used, but I suspect it to be a bad contact and capacitive coupling of the signal due to the low 20mV amplitude.

RE: Rohde and Schwarz RTO64 Probe calibration not working

Gough Lui — Wed, 19 Nov 2025 17:35:50 GMT

Please check your probe hook grabber is fully seated by pushing down until it clicks. Alternatively, remove it and check the probe pin is properly seated. Also check the ground clip is properly clipped into place and is making good contact. Also check the BNC connector in case there is a damaged pin. Try exchanging channel or probe to see if you can eliminate the issue.

Your low amplitude and distorted waveform suggests to me that there is a bad contact.

You should be able to best compensate the probe without the ground clip lead, by lying the tip across the ground hook with the tip in contact with the 1kHz square wave signal loop. There is a probe compensation app to help you dial in the alignment.

RE: Rohde and Schwarz RTO64 Probe calibration not working

dougw — Wed, 19 Nov 2025 16:57:48 GMT

It looks like you have it set for AC coupling - it should be set to DC coupling.

Simulazione batteria ngm202

Simonedb32 — Tue, 24 Sep 2024 11:21:11 GMT

Ciao a tutti, ho una domanda per voi, forse è anche troppo banale.

Sto simulando il comportamento di una batteria a ioni di litio con l'utilizzo di ngm202, sto usando come carico una resistenza di 110 ohm. Durante la fase di scarica va tutto bene, per la fase di carica appena la scelgo, ocp chiude il canale e quindi non avviene la carica. Il problema sta nella corrente che ha un valore positivo molto piccolo? Oppure per simulare la carica devo collegare un generatore di tensione anzi ché una resistenza?