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Many people quote Signal Strength and Signal Quality as an accurate measurement of how strong or how efficient a satellite system is. Is there a difference between Signal Strength and Signal Quality?
What are the differences and how does it affect the indication of received signal on a satellite receive system?
1: Signal Strength
This is a measurement of how strong a signal your receiver is getting from the LNBF. It has nothing to do with how strong of a signal you are getting from a satellite. This is actually the signal strength of the Intermediate Frequency (IF) output from the LNBF.
Note that in most cases your signal strength is always strong – around 90 to 100 percent. Signal strength is just an indication of how strong the received signal is .The receiver should operate with signals up to 100%... However some manufacturers will not guarantee the receiver will operate correctly with low signal strengths. Some require at least 60% for normal operational requirements.
Low signal strength readings can be used as an indication that “something” is wrong between the LNB and the receiver. It can’t tell you what is wrong, but simply that there is a problem. Usually – defective connectors or cable.
2: Signal Quality
This is a measurement of the Bit Error Rate (BER) of the received signal from the satellite. What ever the modulation scheme (QPSK, 8PSK) All of these modulation schemes use a form of Forward Error Correction (FEC) to determine if the signal being sent is actually being properly received without errors. Any received errors will be corrected in the receiver by bit substitution in the FEC process.
The Signal Quality bar on your receiver is basically indicating the receiver Bit Error Rate (BER) from the satellite – and how much, or how little error correction is taking place. The higher the signal quality reading on the receiver means a low Bit Error Rate. Note that signal quality readings are usually between 60 to 80 percent and will provide a very good quality picture “ corresponding to a low Bit error rate”
Low signal quality indications can result from many factors, improper dish alignment; poor cross pole nulling is a major contributor to low signal strength, and low Signal quality. In some cases a dish that is simply not large enough. To provide a signal that exceeds the satellite receiver threshold for a specific service.