186 Chapter 4
Downloading and Using Files
Downloading Directly into Pattern RAM (PRAM)
Modulating and Activating the Carrier
After downloading a file:
1. Set the carrier frequency.
2. Set the carrier amplitude.
3. Turn on modulation.
4. Turn on the RF output.
Viewing a PRAM Waveform
After the waveform data is written to PRAM, the data pattern can be viewed using an oscilloscope. There is
delay (approximately 12-symbols) between a state change in the burst bit and the corresponding effect at the
RF out. This delay varies with symbol rate and filter settings, and requires compensation to advance the
burst bit in the downloaded PRAM file.
Troubleshooting Direct PRAM Download Problems
NOTE Review “Data Requirements and Limitations” on page 183.
Symptom Possible Cause
The transmitted pattern is
interspersed with random,
unwanted data.
Pattern reset bit not set.
Ensure that the pattern reset bit (bit 7, value 128) is set on the last
byte of your downloaded data.
ERROR -223, Too much data PRAM download exceeds the size of PRAM memory.
Either use a smaller pattern or get more memory by ordering the
appropriate hardware option.
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