A "work in progress" Forum heads up - perhaps of interest to the lost rocket,near space balloon & "fox hunting" crowd? It suits a nifty & cheap OUTDOOR application for educational electronics too-
A spot of data sheet sleuthing has revealed a valuable RSSI (Received Signal Strength Indication) outlet at Pin 13 (nominally CAGC) on the cheap (~US$3) Dorji DRA886RX ASK receiver module's SYN470R RF IC. When run from a supply of 3 x AA (~4.5V,with a circuit draw of ~5mA) voltages presented here ranged from ~1.34V (when beside a companion 433 MHz beacon transmitter) to ~2.54V no signal. The ~1.2V swing naturally should be very PICAXEable!
A DMM for V readout (along with a with a simple tape measure Yagi) was initially used, & quite remarkable "beaming" to the signal position resulted. Alternative peak/null indications with a small (piezo transducer) speaker & LED,although simple, proved troublesome in noisy & bright conditions. In contrast the DMM was readily read outdoors (& could be adjusted to suit the application),with it's fine resolution allowing hairs to be almost split at hundreds of metres! Beacon signals could readily be "beamed" onto over several km (near LOS), especially if an elevated vantage point was used. Although the ASK module data sheet assigns it only ~107 dBm (1µV) sensitivity, the setup was so sensitive that it was even able to focus clear across a room onto weak 433 MHz radiation from the super-regenerative circuitry of an Arlec wireless door chime receiver !
The appeal of a tape measure antenna at 433 MHz mainly relates to the flexible elements,as the whole thing can be readily stuffed into a bag. Naturally it's also less likely to snag in vegetation when outdoors as well. Assembly onto "Pope" garden irrigation fittings required little more than a ruler, snippers, hammer (+ old nail for hole punching),self tapping screws & screwdriver. Total cost of antenna materials ~US$10.
I'll eventually write this up as at least an Instructable, but check initial pictures at => https://picasaweb.google.com/113235065280579741262/Dorji_DF
Feedback & insights welcomed. Stan. (ZL2APS)
A spot of data sheet sleuthing has revealed a valuable RSSI (Received Signal Strength Indication) outlet at Pin 13 (nominally CAGC) on the cheap (~US$3) Dorji DRA886RX ASK receiver module's SYN470R RF IC. When run from a supply of 3 x AA (~4.5V,with a circuit draw of ~5mA) voltages presented here ranged from ~1.34V (when beside a companion 433 MHz beacon transmitter) to ~2.54V no signal. The ~1.2V swing naturally should be very PICAXEable!
A DMM for V readout (along with a with a simple tape measure Yagi) was initially used, & quite remarkable "beaming" to the signal position resulted. Alternative peak/null indications with a small (piezo transducer) speaker & LED,although simple, proved troublesome in noisy & bright conditions. In contrast the DMM was readily read outdoors (& could be adjusted to suit the application),with it's fine resolution allowing hairs to be almost split at hundreds of metres! Beacon signals could readily be "beamed" onto over several km (near LOS), especially if an elevated vantage point was used. Although the ASK module data sheet assigns it only ~107 dBm (1µV) sensitivity, the setup was so sensitive that it was even able to focus clear across a room onto weak 433 MHz radiation from the super-regenerative circuitry of an Arlec wireless door chime receiver !
The appeal of a tape measure antenna at 433 MHz mainly relates to the flexible elements,as the whole thing can be readily stuffed into a bag. Naturally it's also less likely to snag in vegetation when outdoors as well. Assembly onto "Pope" garden irrigation fittings required little more than a ruler, snippers, hammer (+ old nail for hole punching),self tapping screws & screwdriver. Total cost of antenna materials ~US$10.
I'll eventually write this up as at least an Instructable, but check initial pictures at => https://picasaweb.google.com/113235065280579741262/Dorji_DF
Feedback & insights welcomed. Stan. (ZL2APS)
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