Using the RSP1 with a noise source aka Scalar Network Analyzer
I've been using my RSP1 along with an inexpensive noise source (from eBay) as a Scalar Network Analyzer. Similar to a conventional spectrum analyzer/tracking generator combination.
With this, I can use the RSP1 to analyze and characterize RF filters, mixers, etc. and also to tune repeater duplexer units. I also have a 10db Directional coupler which I can connect between the noise source and the RSP1, which gives the RSP1 the ability to read return loss which allows for pretty precise antenna resonance & bandwidth measurements.
I thought that it might be good to report my findings with this here so that others may benefit from my experiences.
Results are actually quite good. For comparison, I also have an Instek model GSP-810 1ghz spectrum analyzer in the RF lab here. It has a tracking generator also.
The image below shows the RSP1/Noise Source/Directional Coupler combo sweeping a homebrew 80m double-bazooka antenna, using SDRSharp for display. Other SDR programs such as SDRuno, HDSDR, etc. can be used also with good results. As can be seen, the antenna is most resonant at 3890 khz (center freq in the display):
Next is sweeping a 500khz low-pass filter. Sharp decrease beginning at about 575khz, just as it should be:
So my conclusions are that while the RSP units in combo with noise source are not yet a true substitute for a dedicated spectrum analyzer/tracking generator, they are certainly accurate enough for test purposes and most useful for this. This is a great way to create a useful scalar network analyzer without spending lots of money. But what is really needed here is a good, dedicated spectrum analyzer program for use with the RSP. Such a program would have analyzer features such as markers, separate frequency readouts, reference (top line) level setting, and provisions for power level reading calibration with offset setting for use with external attenuators. I am a software developer and would write the program myself for us all to use but my specialties are in other areas so I do not have the necessary skill.
So get a good noise source to use with your RSP1/RSP2, and experiment!