ARD-2 bulletin page

The ARD-2 is an AUDIO decoder & display unit, so if you feed audio from the external speaker / earphone / headphone socket of your radio into the AF-IN (audio input) of the ARD-2, nothing else is required.

The radio must be capable of AM reception on the airband, have clean sounding audio, provide sufficient audio level to drive the ARD-2, and be capable of operating with the squelch set permanently open.

Possible problems:

1. If you cannot open the squelch permanently, the beginning of transmissions will be chopped off, this will result in corruption of the data and no valid display on the ARD-2. Don't try to scan the ACARS frequencies, you will chop up the signals and no meaningful results will be obtained.

2. You must experiment with audio level from the radio. Too much or too little audio will compromise or prevent decoding. The audio from the radio must be clean with no harshness at the beginning of transmissions (which would indicate AGC compromises, especially with strong signals).

3. Ideally for home use the ARD-2 should be run from a regulated 12V power supply, if using internal batteries, ensure that they are not near exhaustion. If the batteries are low, they will still power the ARD-2 LCD but will not decode ACARS.

Note: When the batteries become nearly flat, the decoding will stop BEFORE the display disappears... if you think that decoding efficiency has dropped, fit new batteries or run the ARD-2 from external DC.

4. The Yupiteru range appear prone to interference from any electrical equipment nearby (including the ARD-2, particularly the MVT7100), consider the use of a filtered screened audio lead. For home use, consider a remoted external aerial. Take a look at the technical bulletin on the subject of noise:

http://www.aoruk.com/ard2bull.htm#noise
http://www.aoruk.com/pdf/pdf/ard2_ad.pdf

5. For good reception of ACARS and NAVTEX, you 'must' first achieve clear reception and solid audio, if the audio is poor, the results will also be poor.

6. Select the local ACARS VHF airband primary frequency in AM mode: 131.550 MHz in the USA, Canada & Pacific, 131.450 MHz in Japan and 131.725 MHz in Europe. New London ACARS frequency from December 1999, 136.900 MHz. Additional frequencies in Europe have been reported to include: 131.525 MHz and 136.925 MHz.

For NAVTEX, use USB on 518kHz (0.518MHz), 424kHz is also used.

For ACARS reception, the AR8000 / AR8200 hand portable radios work fine, in particular the AR5000 and AR3000A provide excellent results.

All electrical equipment has the potential to generate noise, although carefully designed to minimise such noise
(and adhering to the new CE electrical requirements), noise can be passed from the ARD-2 to the receive station.

If noise is encountered, attempt to physically separate the receiver and ARD-2 when possible, the use of remote aerials can also be of assistance. For base station use, an external aerial and good RF earth should result in very little noise, similarly at airports, higher signal strength should provide good results. Some receiver models appear more prone to

If using a receiver which has AFC (Automatic Frequency Control) or NL (Noise Limiter), ensure you have both the AFC and NL off, if they are on, the radio usually produces a cluck / buzz when re-tuning which will effect results. If your receiver has narrow and wide filters for AM reception (NAM, WAM) start by using the standard bandwidth (AM), narrow AM will severely limit the audio bandwidth, you can experiment with WIDE AM.

The most important factor always seems to be the audio level, only very small changes are required.

Note: With care, a capacitor and resistor can be fitted into each jack plug and coaxial screened cable used to make up the interconnecting lead. The values chosen are not critical, 0.1uF capacitors would be equally suitable. Similarly, 10nF may give better results in some cases. The above values were chosen purely because they were to hand and were of a suitable physical size to fit inside of the jack plug. Your dealer may be able to assist for a nominal charge.

Due to continuous developments, AOR reserves the right to make design and specification changes for product improvement without prior notice. The performance specification figures indicated are nominal values of production units. There may be some deviation from these values in individual units.

ARD-2 Bulletin Page