Frequency Objects Compatible with the Kenwood and Yaesu APRS Radios

One Button QSY

The Kenwood TM-D710A & TH-D72A as well as the Yaesu FTM-350 & 400 offer a ‘one button qsy’ feature to tune quickly to a local voice repeater, setting shift and tone upon receipt of a properly formatted APRS frequency object.  This feature is convenient to travelers as well as local users.

Although the full details are here, the following examples show the working format determined from actual testing.

VHF Voice Repeater:

;146.85TRF*111111z4804.29N/09606.79WrToff -060 Sufficient for Kenwood series

;146.85TRF*111111z4804.29N/09606.79Wr146.850MHz Toff -060 Adds Yaesu compatibility

This is for a VHF voice repeater near Thief River Falls MN, thus the abbreviation TRF, wideband modulation, as indicated by the capital T, with no tone.  -060, which must be 3 decimal digits in units of 10 KHz, sets a shift of -600 KHz, and is separated from Toff by a single space. The Yaesu radios do not interpret the frequency specification as part of the object name, immediately following the “;”, instead they require the frequency to be specified later in the packet as 146.850MHz as shown above, with 3 digits following the decimal point, followed by MHz. This repetition of the frequency lengthens the packet, but is needed to allow the object to be interpreted by both the Kenwood and Yaesu radios.

If the frequency were 146.855 MHz rather than 146.85 MHz, the frequency object would be:

;146.855TR*111111z4804.29N/09606.79Wr146.855MHz Toff -060

Since the frequency plus the identifier must be 9 bytes long, the identifier has been shortened to TR.  The 3, or 2, letter abbreviation is useful to the traveler as an indication of the repeater’s location, but also helps in making the object name unique.  I do not recommend using spaces, – or +, instead pick an abbreviation that is meaningful to the location.  A + sign in the name is incompatible with FINDU.COM.

When specifying a frequency object name, you should confirm that your choice is not already in use.  To check this is to go to http://www.findu.com/cgi-bin/find.cgi?146.85TRF and then replace 146.85TRF by your proposed object name.  If it is already in use pick something else.

While it is true that the offset typically isn’t required, on 2 meters the D710A will use the radio’s default offset for the frequency, here is an example of where it is required:

;147.00RSV*111111z4847.94N/09505.14Wr147.000MHz T123 -060

This repeater is non standard, normally 147.00 MHz would default to a +600 KHz offset, yet this repeater uses a -600 KHz offset.  Without the stated offset the radio would use +600 KHz.  I have chosen to always include the offset for uniformity.  For UHF the D710A requires it!

UHF Voice Repeater:

;444.80TRF*111111z4807.60N/09610.63Wr444.800MHz T156 +500

This UHF voice repeater uses wideband modulation as indicated by the capital T, almost all ham repeaters are wideband, with a tone of 156.7 Hz. The tone frequency is always truncated to 3 digits and must include a leading 0 if needed to make it 3 digits long.   The offset is +5.0 Mhz as indicated by +500, which is in units of 10 KHz. A single space separates the tone from the offset.  If the offset were not stated, the D710A would not apply any offset, and you couldn’t raise the repeater.  For this reason, as well as the 147.00RSV example, I have chosen to always provide the offset information.

Optional Items:

The prior examples are the bare minimum.  You may add optional items:

R30m                    Indicates an approximate repeater range of 30 miles.

NETxxxxxx     Indicates if there is a weekly net on this repeater, e.g., NET Tu9PM

The total space used is 10 bytes including a trailing space.

MTGxxxxx Indicates there is a monthly club meeting, e.g., MTG3rdTH

The total space used is 8 bytes.

An example including optional elements is:

;146.94GFK*111111z4754.63N/09704.11Wr146.940MHz Toff -060 R30m NET M 9PM

Optional items require additional transmission time, and may be of limited value.  I rarely include them.

You may see the some of the frequency objects I transmit at http://aprs.fi/?c=raw&call=AE5E-5

Recommended Paths and Repetition Rates

Frequency Objects are intended primarily for mobiles traveling in the immediate area and thus transmitting them beyond where the repeater can be reached is unnecessary QRM. Since the potential user of the voice repeater may be traveling through your area these packets must be transmitted frequently.  A reasonable repetition rate would be 600 seconds.

If you are sending these from a digipeater which is heard by a local IGate, a path of NULL will be adequate.  Such a packet will not be digipeated, nor should it.  I specifically use the actual word NULL having discovered that a null entry for the path in a UIDIGI-ROM digipeater produces a corrupted packet.

If a single digipeat will be required to cover the area served by the voice repeater or to reach an IGate, then the path could be the specific call of the digipeater that will be required to digipeat the packet to the needed service area.  Alternatively a path of WIDE2-1 could be used, although this may result in more than one digipeater repeating the packet unnecessarily.

You can see your frequency object on a map such as at APRS.FI.   

Additional Information

All the details can be found here http://www.aprs.org/localinfo.html.  However I created this simplified document to aid sysops after discovering that few digipeaters were sending D710A compatible frequency objects.  The formats which I present correctly set up the TM-D710A (K version) for one button QSY.

Ron Stordahl, AE5E