TRIMBLE EXTERNAL CLOCKS:
It depends on the specific Trimble device.
For Trimble GPS-disciplined oscillators (GPSDOs) commonly used as 10 MHz frequency references:
- The 10 MHz reference output is usually a sine wave, typically around +7 to +13 dBm into 50 Ω, intended to drive test equipment, SDRs, and frequency standards.
- The 1 PPS (pulse per second) output is a square-wave pulse, typically TTL or CMOS levels (e.g. 0–5 V or 0–3.3 V depending on the model).
If you mean one of the surplus Trimble units popular with radio amateurs, such as the Thunderbolt, Thunderbolt E, or Resolution T, the 10 MHz output is a sine wave, while the 1 PPS output is a square pulse.
LEO BODNAR EXTERNAL CLOCKS:
On the Leo Bodnar GPS reference clock (including the Mini GPS Reference Clock and LBE-1420 series), the RF reference output is not a sine wave.
It outputs:
- Square wave
- 3.3 V CMOS logic levels
- 50 Ω source impedance
- User-programmable from approximately 1 Hz up to hundreds of MHz (or 1.4 GHz on some models).
For a 10 MHz output, it is still a 3.3 V CMOS square wave. Many SDRs and frequency-reference inputs accept this directly. If a piece of equipment requires a 10 MHz sine wave (as some laboratory instruments do), you would need to pass the output through a suitable low-pass or band-pass filter to extract the fundamental sine component.
If you’re considering it for your SDRplay RSPduo, PlutoSDR, or another SDR, let me know which device, and I can tell you whether the Leo Bodnar’s square-wave output is directly compatible.