NTP001 Signal Strength and GNSS system

[lovocorp]

I just spoke with William from 1st time support. I am moving this conversation to the Community.

We’re deploying an NTP001 on an air-gapped network where GNSS is the only time source, with no upstream NTP available, and the antenna has to sit at an interior window. We need to validate its reliability and have three questions.

1. Holdover. When the unit loses satellite lock, what keeps time, and how well? Specifically, what oscillator does the NTP001 use (TCXO, OCXO, other), what is the expected timekeeping drift during a GNSS outage in ppm or seconds per day, and does the firmware discipline the internal clock from GNSS while locked to improve short-term holdover after a dropout? Is there any holdover or fallback feature we should configure?

2. Constellations. The current firmware lets us select only one GNSS system at a time in the GNSS mode setting. Is concurrent multi-constellation operation supported, or is it on the roadmap for a future firmware?

3. Viewing signal strength. Is there a supported way to see per-satellite signal strength (C/No) on a locked unit? The web interface doesn’t appear to show it. Can we read it through the CLI (for example a gpsctl command), through the raw NMEA stream and if so what is the device path, through an SNMP OID or MIB, or through an API? If SNMP is supported, could you also send the MIB file for the unit so we can poll lock state and signal strength for unattended monitoring? Any documentation links would help.

[Vilius]

Greetings, @lovocorp ,

Welcome to Teltonika Community!

Thank you for your questions, I will try to address them one by one:

@lovocorp

Holdover. When the unit loses satellite lock, what keeps time, and how well? Specifically, what oscillator does the NTP001 use (TCXO, OCXO, other), what is the expected timekeeping drift during a GNSS outage in ppm or seconds per day, and does the firmware discipline the internal clock from GNSS while locked to improve short-term holdover after a dropout? Is there any holdover or fallback feature we should configure?

I have forwarded this question to our R&D team for clarification and I will update you once I have more information regarding this.

@lovocorp

Constellations. The current firmware lets us select only one GNSS system at a time in the GNSS mode setting. Is concurrent multi-constellation operation supported, or is it on the roadmap for a future firmware?

As for now, only one GNSS mode is available at a time, I asked if the R&D is planning to change this functionality in future releases / updates.

@lovocorp

Viewing signal strength. Is there a supported way to see per-satellite signal strength (C/No) on a locked unit? The web interface doesn’t appear to show it. Can we read it through the CLI (for example a gpsctl command), through the raw NMEA stream and if so what is the device path, through an SNMP OID or MIB, or through an API? If SNMP is supported, could you also send the MIB file for the unit so we can poll lock state and signal strength for unattended monitoring? Any documentation links would help.

Regarding the signal strength, as for today, there is no API implemented for NTP001 device, SNMP variables also does not contain any variables that would be relevant to GNSS signal strength. You can find a list of the available SNMP variables here:

https://wiki.teltonika-networks.com/view/NTP001_SNMP#SNMP_variables_list

Regarding the CLI approach, I am currently testing to see if it is possible to retrieve those values using CLI.

I will inform you as soon as I have an update on the matter.

Best regards,
V.