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This is a percentage signal level of maximum, above which the transmitter will be keyed down

(switched on). Its purpose is to ignore very low amplitude audio signals at the start of a raised

cosine keying envelope, whose audio tone could be decoded inaccurately due to quantization

error. This is discussed further in the Design section of this manual in the Audio Frequency

Analysis section. The default value of 80% should be fine for all purposes. The value should not

be set too close to 99%, since higher frequency audio where the number of samples per cycle is

small, may not contain a value sufficient to trigger this threshold in every cycle.

Fall threshold

This is a percentage signal level of maximum, below which the transmitter will be keyed up

(switched off). Its purpose is to ignore very low amplitude audio signals at the end of a raised

cosine keying envelope, whose audio tone could be decoded inaccurately due to quantization

error. This is discussed further in the Design section of this manual in the Audio Frequency

Analysis section. The default value of 60% should be fine for all purposes. The value should not

exceed (or be close to) the Rise threshold parameter, otherwise the transmitter will be repeatedly

keyed on and off falsely.

Minimum cycles

This parameter specifies the minimum number of audio cycles to use, in the measurement of

audio cycle period, for audio frequency calculation. This parameter is used in conjunction with the

Minimum samples parameter: both conditions must be satisfied in order for an audio frequency

measurement to be completed. This parameter is discussed further in the Design section of this

manual in the Audio Frequency Analysis section. The default value of 1 should be fine for all

purposes.

Minimum samples

480

This parameter specifies the minimum number of audio samples to use, in the measurement of

audio cycle period, for audio frequency calculation. This parameter is used in conjunction with the

QMX operating manual Minimum samples parameter: both conditions must be satisfied in order

for an audio frequency measurement to be completed. This parameter is discussed further in the

Design section of this manual in the Audio Frequency Analysis section. The default value of 480

should be fine for all purposes.

Bearing in mind that there are 48,000 audio samples per second, a value of 480 specifies a

minimum 0.01 second audio measurement period. In other words, there will be 100 measurements

of the audio frequency, per second, in this default configuration. This is sufficient to ensure that

high audio frequencies are measured accurately. In the unlikely event that frequencies below

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