SDRplay 2 TCXO PN and external locking

Post information or questions regarding SDRplay products here
Conrad Farlow
Posts: 12
Joined: Fri May 19, 2017 11:02 am

SDRplay 2 TCXO PN and external locking

Postby Conrad Farlow » Fri May 19, 2017 11:29 am

Hello all, I have 24MHz GPSDO. I was wondering what the PN of the internal TCXO is, just to ascertain that my 24MHz TCXO will not degrade performance significantly. I am just running the 24 MHz oscillator on an FSUP to measure the PN this afternoon.

I presume that there is a PLL on the TXCO when an external 24MHz signal is present?

Regards

Conrad Farlow PA5Y
Last edited by Conrad Farlow on Thu Jan 01, 1970 12:00 am, edited 0 times in total.
Reason: No reason

Conrad Farlow
Posts: 12
Joined: Fri May 19, 2017 11:02 am

Re: SDRplay 2 TCXO PN and external locking

Postby Conrad Farlow » Mon May 22, 2017 12:06 pm

So this information is not available? Ok then I will measure it myself.

Regards

Conrad PA5Y
Last edited by Conrad Farlow on Thu Jan 01, 1970 12:00 am, edited 0 times in total.
Reason: No reason

Conrad Farlow
Posts: 12
Joined: Fri May 19, 2017 11:02 am

Re: SDRplay 2 TCXO PN and external locking

Postby Conrad Farlow » Mon May 22, 2017 12:23 pm

I found the schematics here:
http://sdrplay.com/docs/SDRplay_RSP_Schematics_r2p2.pdf

So I see from this that the TCXO is not shown as such, rather a simple Xtal oscillator. The datasheet shows a TCXO and I have found the frequency accuracy to be quite good out of the box.

What is also not evident on the schematic is how the external clock is connected. I like to know these things out of interest.

Perhaps you could give me the part number of the TCXO and I can look up the spec for myself?

Regards

Conrad PA5Y
Last edited by Conrad Farlow on Thu Jan 01, 1970 12:00 am, edited 0 times in total.
Reason: No reason

Conrad Farlow
Posts: 12
Joined: Fri May 19, 2017 11:02 am

Re: SDRplay 2 TCXO PN and external locking

Postby Conrad Farlow » Wed May 24, 2017 2:45 pm

Did I post this in the wrong place, nobody has anything to say about this? I am overwhelmed to be honest.

Regards

Conrad
Last edited by Conrad Farlow on Thu Jan 01, 1970 12:00 am, edited 0 times in total.
Reason: No reason

Tech_Support
Posts: 203
Joined: Mon Jun 01, 2015 7:00 pm

Re: SDRplay 2 TCXO PN and external locking

Postby Tech_Support » Fri May 26, 2017 2:45 pm

Hello Conrad,
The schematics you have shown are for the RSP1 and not the RSP2. The RSP2 does use a TCXO. We have an application note on how to set the RSP2 up with an external clock. It can be found on our website at:

http://www.sdrplay.com/docs/SDRplay_RSP ... e_R1P0.pdf

Sincerely

SDRplay Tech_Support

Reason: No reason

Conrad Farlow
Posts: 12
Joined: Fri May 19, 2017 11:02 am

Re: SDRplay 2 TCXO PN and external locking

Postby Conrad Farlow » Sat Jul 08, 2017 4:33 pm

OK, I know how to set it up, I have been using it locked to a 24MHz oscillator for quite a few weeks now but I still do not know anything about the TCXO performance. I want to know the phase noise performance of the TCXO and if it is locked or if there is just a simple RF detector that switches the LO source from internal TCXO to the external one. Both approaches are possible and each has advantages and disadvantages.

I believe that my external LO does not degrade the performance but I am at the limits of what I can measure. If I had some numbers I could make a more informed decision. Surely it's not a secret?

It's a very good product for the money that's for sure.

Regards

Conrad Farlow PA5Y

Reason: No reason

Tech_Support
Posts: 203
Joined: Mon Jun 01, 2015 7:00 pm

Re: SDRplay 2 TCXO PN and external locking

Postby Tech_Support » Sat Jul 08, 2017 5:14 pm

Hello Conrad,
If you apply 0v DC to the reference input it switches from using the internal TCXO to the external clock. It is important that the clock is present and stable before the RSP2 is powered up as dynamically transitioning from one clock regime to another can cause glitches that leads to a lock up on an internal microprocessor within the RSP2 chipset.

Sincerely

SDRplay Tech_Support

Reason: No reason

Conrad Farlow
Posts: 12
Joined: Fri May 19, 2017 11:02 am

Re: SDRplay 2 TCXO PN and external locking

Postby Conrad Farlow » Sat Jul 08, 2017 10:02 pm

Hi, yes it all works perfectly well thanks.

Thanks for clarifying that there is a switch and not a PLL operating on the TCXO, I suspected that would be the case.

My question is not a 'how to' or operational one but one of performance.

I will ask again perhaps a little more directly.

Is there ANY chance of getting the phase noise spec for the internal TCXO? I have measured my external synthesised source on an FSUP at my work place, it is good but I do not expect it to be as good as a decent quality TCXO.

Is there a schematic and BOM available? That would answer all my questions.

On the air I have not had a situation where I can hear the difference between the internal and external oscillator but I would still rather know the numbers.

Regards

Conrad Farlow PA5Y

Reason: No reason

Tech_Support
Posts: 203
Joined: Mon Jun 01, 2015 7:00 pm

Re: SDRplay 2 TCXO PN and external locking

Postby Tech_Support » Sun Jul 09, 2017 9:18 pm

Hello Conrad,
The TCXO has a phase noise spec of -130 dBc/Hz at a 1 kHz offset. It isn't clear what type of signals you are receiving but the phase noise of the reference clock will have little impact on the key parameters that affect reception of various kinds of signals, namely the overall phase jitter (for digital signals) and reciprocal mixing for blocking, unless the performance is very bad. In the case of jitter, the performance is really determined by the noise floor of the synthesizer PFD and the loop bandwidth. In the case of reciprocal mixing, the performance is really determined by the noise floor of the LO path. Unless the phase noise performance of your signal generator is very poor, it is unlikely to have any noticeable effect on the reception performance of your RSP2.

I am afraid that we do not make the schematic of the RSP2 publicly available.

If you have any specific support related questions, please open a support ticket via the contacts section on our website. This forum is really a vehicle for the community of RSP users to exchange knowledge and information. Whilst we endeavour to keep track of what is posted, we do sometimes miss some posts, which is why we do not encourage the use of this forum to post support related questions.

Sincerely

SDRplay Tech_Support

Reason: No reason


Return to “SDRplay related”

Who is online

Users browsing this forum: No registered users and 5 guests