Frequency accuracy and receiver performance!(hlp)

Hi all,

I have some questions on the frequency accuracy or stability: (Please help me analyze it)

1) What's the frequency accuracy? what's the frequency stability? what are the differences between the accuracy and stability?

2) There is a specification on crystal, frequency stability xxppm. How to define the PPM? About the crystal ppm specification, is there a time range to define it?

3) I know the crystal stability can affect the modulate/demod, but how to analyze the influence?

4) Are there any literatures on such three topics?

Thanks!

Best Regards!
Dopradar

Hi,

Frequency accuracy

The degree of conformity of a measured or calculated frequency to its definition. Since accuracy is related to the offset from an ideal value, frequency accuracy is usually stated in terms of the frequency offset.

Frequency deviation

The amount by which a frequency differs from a prescribed value, such as the amount an oscillator frequency drifts from its nominal frequency. In frequency modulation, the absolute difference between (a) the maximum permissible instantaneous frequency of the modulated wave or the minimum permissible instantaneous frequency of the modulated wave and (b) the carrier frequency.

Frequency stability

The amount of frequency deviation from the ambient temperature frequency over the operating temperature range. This deviation is associated with a set of operating conditions including operating temperature range, load capacitance, and drive level. This parameter is specified with a maximum and minimum frequency deviation, expressed in percent (%) or parts per million (ppm). The frequency stability is primarily determined by the type of quartz cut and angle of the quartz cut. Some of the secondary factors influencing frequency stability include mode of operation, drive level, load capacitance, and mechanical design. The frequency stability is the allowable deviation, in parts per million (ppm), over a specified temperature range. The deviation is referenced to the measured frequency at +25°C.

Also see this page for clear distinction:
http://www.ieee-uffc.org/freqcontrol...g/vigaccur.htm

If this all was of some use to you then plesae mark 'helped me'.

Regards,

jiveshgovil,

How does the frequency stability affect the demodulation?

Thanks!
Dopradar