Modes of Operation | Signal Hound
prevent the circular buffers from wrapping. We suggest a separate polling thread and synchronized data
structure (buffer) for retrieving the samples and using them in your application.
NOTE: Decimation / Filtering / Calibration occur on the PC and can be processor intensive on certain
hardware. Please characterize the processor load.
I/Q streaming is also the only mode in which you can time stamp data (See Appendix:Using a GPS
Reciever to Time-Stamp Data) and determine external trigger locations (See bbFetchRaw()).
Gain and Attenuation in the Streaming Mode
Gain and attenuation are used to control the path the RF takes through the device. Selecting the proper
gain and attenuation settings greatly affect the dynamic range of the resulting signal. When gain and
attenuation are set to automatic, the reference level is used to control the internal amplifiers and
attenuators. Choosing a reference level slightly above the maximum expected power level ensures the
device engages the best possible configuration. Manually configuring gain and attenuation should only
be used after testing and observation.
Audio Demodulation
Audio demodulation can be achieved using bbConfigureDemod(), bbFetchAudio(), and
bbInitiate(). See bbConfigureDemod() to see which types of demodulation can be performed.
Settings such as gain, attenuation, reference level, and center frequency affect the underlying signal to
be demodulated.
bbConfigureDemod() is used to specify the type of demodulation and the characteristics of the filters.
Once desired settings are chosen, use bbInitiate() to begin streaming data. Once the device is
streaming it is possible to continue to change the audio settings via bbConfigureDemod() as long as the
updated center frequency is not +/- 8 MHz of the value specified when bbInitiate() was called. The
center frequency is specified in bbConfigureDemod().
Once the device is streaming, use bbFetchAudio() to retrieve 4096 audio samples for an audio sample
rate of 32k.
Scalar Network Analysis
When a Signal Hound tracking generator is paired together with a BB60C spectrum analyzer, the
products can function as a scalar network analyzer to perform insertion loss measurements, or return
loss measurements by adding a directional coupler. Throughout this document, this functionality will be
referred to as tracking generator (or TG) sweeps.
Scalar Network Analysis can be realized by following these steps
1. Ensure a Signal Hound BB60C spectrum analyzer and tracking generator is connected to your PC.
2. Open the spectrum analyzer through normal means.
3. Associate a tracking generator to a spectrum analyzer by calling bbAttachTg. At this point, if a TG
is present, it is claimed by the API and cannot be discovered again until bbCloseDevice is called.
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