VDL2 to AMDSB Interferences 13

1

• VDL2 to AM-DSB Interferences (1/3)

• TRADITIONAL METHOD TO QUANTIFY A VOICE LINK
  DEGRADATION
• (SN)/N Degradation
• HOWEVER, IN THE CASE OF A VDL2 UNWANTED SIGNAL
• Short spurious pulses can be observed before the
  (SN)/N degradation (at the very moment when the
  VDL2 transmission begins)
• These pulses are heared as "clocks" added to the
  voice
• Auditive discomfort depends on the repetiton
  cycle
• SIGNAL/PULSE RATIO CHARACTERISTIC
• Definition of a "Signal/Pulse Ratio"
• S/P 6 dB has been validated for VDL2 by AMCP
  WGB
• Various results according to the receiver type

2

• VDL2 to AM-DSB Interferences (2/3)

(for S/P6dB)
3

• VDL2 to AM-DSB Interferences (3/3)

• TECHNICAL ANALYSIS TO EXPLAIN VARIOUS RESULTS
  ACCORDING TO THE VERSION
• Type 1
• Receiver front end is equipped with high signals
  protection
• S/P results depend on the protection threshold
  adjustment
• Type 2
• equipped with an "interlocking system"
• slight differences in front end adjustments
• HOW CAN RESULTS BE IMPROVED ?
• Protection adjustment change for type 1
• Then, same results as for type 2
• This minor change has been validated
• (no impact on other characteristics)