The superregenerative RF receiver modules used in most of the wireless projects have both a digital and linear (or analog) output. The linear/analog output can be used (along with a microcontroller) as an RSSI (Received Signal Strength Indicator) to tune the receiver module to the desired frequency. The modules themselves have a tuning slug and are capable of tuning over a fairly broad frequency range. A microcontroller can be configured to output an RSSI value.

Start with a transmitter located near the receiver, transmitting continuously, using either no receiving antenna or a simple 1/4 wave wire. Tune the receiver for a maximum RSSI value. Move the transmitter to a point 25-30 feet distant and repeat. The second tuning should be with the normal receiving antenna. The first tuning will get you close and the second will fine tune it.

The 'scope screenshot below shows why a microcontroller is useful. The top trace is the linear/analog pin while the lower trace is the digital pin. The microcontroller lets us time ADC readings on the analog output for a pulse and the following space with the difference being an excellent indicator of signal strength.

Alternately, you can use a peak detector with a voltmeter.

NOTE: It's also possible to get within the ballpark by connecting the digital signal to Line In on a soundcard and listening for the data burst. You will still need to fine tune as above.

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