![[sweep.png]](http://www.tima.com/%7Edjones/sweep.png)
Spectrum Check for DRM Digital SSTV
Efficient transmission of DRM digital SSTV signals require linear
audio reproduction from transmitter to receiver through the range of
350 Hz to 2800 Hz. Filters will disrupt the signal and cause the DRM
digital SSTV decode to fail. The waterfall display in DIGTRX can be
used to check and verify the proper reception of this range of
frequencies.
350 Hz to 2800 Hz Sweep Tone
sweep.wav
To download on some browsers, just hold down the "Shift" key before clicking the link.
Sweep Tone as a "Precoded waterfall message" (.PMW)
sweep.pmw
Download to your DIGTRX\precoded folder.
Check transmit linearity
Play this sweep tone over the air and watch your power output. Use
a low audio level that would give a power output of 5 to 30 watts. The
output power should not vary more than 10% for the range of the sweep.
Check receive linearity
Have a station play this sweep tone over the air and watch the
waterfall display in DIGTRX for the line produced. The line should be
straight, continuous and free of any dropout. See the image below.