Skip to content
aprs.helpAPRS Knowledge & Resources

Repeater objects in APRS

This document describes a practical format for a repeater object in APRS. It is intended as a help file for a user creating frequency objects, especially for FM repeaters.

The goal is to prepare a frame that is readable for operators, consistent with APRS Frequency Objects practice, and supported as well as possible by mobile APRS radios.

1. Example object frame

Section titled “1. Example object frame”
;438.462WX*111111z5218.54N/02113.09Er438.462MHz C127 -760 R10k SR5WWL

The frame consists of several logical parts:

;438.462WX*111111z5218.54N/02113.09Er438.462MHz C127 -760 R10k SR5WWL
|        | |      |        | |        | |          |    |    |    |
|        | |      |        | |        | |          |    |    |    +-- comment, callsign, or description
|        | |      |        | |        | |          |    |    +------- repeater range
|        | |      |        | |        | |          |    +------------ repeater shift
|        | |      |        | |        | |          +----------------- CTCSS tone and FM width
|        | |      |        | |        +---------------------------- symbol
|        | |      |        | +------------------------------------- longitude
|        | |      |        +--------------------------------------- symbol table
|        | |      +------------------------------------------------ latitude
|        | +------------------------------------------------------- timestamp
|        +--------------------------------------------------------- object name
+------------------------------------------------------------------ frame type: object

2. Frame type: object

Section titled “2. Frame type: object”

An APRS object starts with a semicolon:

;

After the semicolon comes the object name:

;438.462WX

In the example, the object name contains the frequency and a local suffix:

438.462WX

where:

438.462  - repeater frequency shown as the object name
WX       - local suffix, in Poland often a county code

3. Object name: frequency and local suffix

Section titled “3. Object name: frequency and local suffix”

For repeater objects, it is recommended that the object name starts with the frequency:

438.462WX
145.600WA
145.775KR

This notation is intentional. In APRS repeater and frequency objects, putting the frequency in the object name improves readability on mobile APRS radios. The radio shows the object name in the station list, so the operator can immediately see the repeater frequency without opening the object details.

The frequency should also be repeated in the object comment, for example:

438.462MHz C127 -760 R10k SR5WWL

The first occurrence of the frequency, in the object name, is mainly for readability in the object list. The second occurrence, in the comment, is part of the frequency information and may be used by radios or applications for QSY/TUNE functions or for presenting repeater parameters.

The frequency in the name and the frequency in the comment should not be treated as an incorrect duplicate. It is a deliberate compromise resulting from compatibility and practical use of frequency objects.

4. Object name uniqueness

Section titled “4. Object name uniqueness”

The APRS object name has a limited length, so the notation:

frequency + local suffix

is a compromise between readability and uniqueness.

Example:

438.462WX

means an object for frequency 438.462 MHz with local suffix WX.

In Poland, a county code is often used as the suffix. This helps distinguish repeater objects operating on the same frequency in different locations.

For permanent objects, however, remember that the object may enter the entire APRS-IS network. A local suffix such as a county code reduces the risk of local collisions, but it does not fully guarantee global uniqueness.

Practical rule:

recommended scheme:
    frequency + local suffix
    example: 438.462WX


recommendation:
    the object name should start with the frequency


warning:
    for permanent objects sent to APRS-IS, check
    whether the name is as globally unique as possible

If the repeater has a well-known callsign, name, or identifier, it can be placed in the final comment instead of removing the frequency from the object name.

5. Alive/dead flag

Section titled “5. Alive/dead flag”

After the object name comes the alive/dead flag:

*

Example:

;438.462WX*

Meaning:

*  - active object
_  - deleted or inactive object

For a normal working repeater, use *.

6. Timestamp

Section titled “6. Timestamp”

The example uses:

111111z

Full fragment:

;438.462WX*111111z

The 111111z timestamp is often used as a fixed timestamp for permanent objects.

Practical rule:

fixed or permanent object:
    111111z


temporary object:
    current UTC time generated on each transmission

For a fixed object, correct regular refreshing of the object is more important than reporting the exact time when it was generated.

7. Coordinates and symbol

Section titled “7. Coordinates and symbol”

Example position:

5218.54N/02113.09Er

Breakdown:

5218.54N   latitude
/          symbol table
02113.09E  longitude
r          symbol

For the repeater object in the example, symbol r is used.

8. Repeater frequency in the comment

Section titled “8. Repeater frequency in the comment”

After the position, provide the repeater operating frequency:

438.462MHz

Recommended format:

xxx.xxxMHz

Examples:

145.600MHz
438.462MHz
439.000MHz

The frequency in the comment should match the frequency used in the object name.

Correct example:

;438.462WX*111111z5218.54N/02113.09Er438.462MHz C127 -760 R10k SR5WWL

Suspicious example:

;438.462WX*111111z5218.54N/02113.09Er439.000MHz C127 -760 R10k SR5WWL

In the second example, the object name suggests 438.462 MHz, but the comment gives 439.000 MHz. Such notation may mislead the operator.

9. CTCSS, tone, and FM width

Section titled “9. CTCSS, tone, and FM width”

In the example:

C127

This means information about the CTCSS tone and repeater mode.

Meaning of letters:

t and c  - narrow FM
T and C  - wide FM


t and T  - repeater opens with tone
c and C  - repeater opens with tone and transmits tone

Example interpretation:

T127  - wide FM, repeater opens with 127 Hz tone
C127  - wide FM, repeater opens with 127 Hz tone and transmits tone
t127  - narrow FM, repeater opens with 127 Hz tone
c127  - narrow FM, repeater opens with 127 Hz tone and transmits tone

It is worth keeping a three-digit format when the tone has fewer than three digits:

T088
c088

10. Repeater shift

Section titled “10. Repeater shift”

In the example:

-760

It means shift -7.6 MHz.

Notation rule:

-760  -> shift -7.6 MHz
-060  -> shift -600 kHz
+760  -> shift +7.6 MHz
+060  -> shift +600 kHz

So the value is written as the offset without a decimal separator.

Examples:

145.600MHz -060
438.462MHz -760
439.000MHz +760

11. Repeater range: Rxxk / Rxxm

Section titled “11. Repeater range: Rxxk / Rxxm”

For repeater objects, the range can be given as:

Rxxk
Rxxm

Meaning:

R10k  - range about 10 km
R25k  - range about 25 km
R15m  - range about 15 miles

In the example:

R10k

so the declared repeater range is about 10 km.

For repeater objects, the Rxxk or Rxxm notation is preferred. It should not be confused with the classic RNGxxxx extension, which is a different mechanism for describing radio coverage.

12. Comment, callsign, or description

Section titled “12. Comment, callsign, or description”

At the end, you can place a callsign, repeater name, or short description:

SR5WWL

Full ending fragment:

438.462MHz C127 -760 R10k SR5WWL

The comment should be short. An APRS frame is not a good place for long descriptions, website addresses, or multi-sentence information.

Section titled “13. Recommended field order in the comment”

For readability and compatibility, it is worth keeping a fixed order:

frequency mode/CTCSS shift range comment

Example:

438.462MHz C127 -760 R10k SR5WWL

Other examples:

145.600MHz T103 -060 R25k SR9ABC
439.000MHz C123 +760 R30k Local
145.775MHz c088 -060 R15k SR5YYY
Section titled “14. Recommended form or generator fields”

When creating a repeater object, a simple generator that builds the object name and comment from separate fields is helpful.

Suggested fields:

Object name:
    438.462WX


Object name mode:
    frequency + local suffix
    custom name


Local suffix:
    WX


Frequency:
    438.462


CTCSS tone:
    127


Tone mode:
    opens with tone
    opens with tone and transmits tone


FM width:
    narrow FM
    wide FM


Shift:
    -7.6 MHz
    -0.6 MHz
    +0.6 MHz
    +7.6 MHz
    custom


Range:
    10


Range unit:
    km
    miles


Comment:
    SR5WWL

Result:

object name:
    438.462WX


comment:
    438.462MHz C127 -760 R10k SR5WWL

The generator should ensure that the frequency is visible both in the object name and in the comment. The frequency should not be removed from the name only because it already appears in the comment.

For a permanent object sent to APRS-IS, it is worth showing a warning:

Names of permanent objects should be as globally unique as possible.
The frequency + local suffix scheme is recommended for readability on APRS radios,
but it does not guarantee full uniqueness across the entire APRS-IS network.
Section titled “15. Recommended validation”

Suggested validation rules:

object name:
    required
    recommended format for repeaters: frequency + local suffix
    example: 438.462WX
    warning if a permanent object is to be sent to APRS-IS
    and the name looks too generic or does not contain a suffix


frequency:
    required
    format xxx.xxx


consistency of name and comment:
    the frequency from the object name should match
    the frequency in the comment, if both are given


CTCSS:
    optional
    only popular CTCSS values or a 2-3 digit number


tone mode:
    t / T / c / C


shift:
    optional
    format +xxx or -xxx


range:
    optional
    format Rxxk or Rxxm


comment:
    optional
    short text without overloading the frame

Validation should help the user instead of blocking all unusual cases. For an informed user, it is worth keeping the option of manual correction.

16. Ready-made object examples

Section titled “16. Ready-made object examples”

UHF repeater, wide FM, CTCSS, shift -7.6 MHz

Section titled “UHF repeater, wide FM, CTCSS, shift -7.6 MHz”
;438.462WX*111111z5218.54N/02113.09Er438.462MHz C127 -760 R10k SR5WWL

VHF repeater, wide FM, tone on input, shift -600 kHz

Section titled “VHF repeater, wide FM, tone on input, shift -600 kHz”
;145.600WA*111111z5215.00N/02055.00Er145.600MHz T103 -060 R25k SR5XXX

VHF repeater, narrow FM, tone on input and output

Section titled “VHF repeater, narrow FM, tone on input and output”
;145.775KR*111111z5215.00N/02055.00Er145.775MHz c088 -060 R15k SR5YYY

17. How to read the object details

Section titled “17. How to read the object details”

From the example frame:

;438.462WX*111111z5218.54N/02113.09Er438.462MHz C127 -760 R10k SR5WWL

you can read:

Object name: 438.462WX
Frequency from name: 438.462 MHz
Local suffix: WX
Position: 52°18.54'N, 21°13.09'E
Symbol: r
Frequency: 438.462 MHz
CTCSS: 127 Hz
FM width: wide
Tone mode: opens with tone and transmits tone
Shift: -7.6 MHz
Range: 10 km
Description: SR5WWL

18. Quick reference

Section titled “18. Quick reference”
;             start of object
438.462WX     object name: frequency + local suffix
*             active object
_             deleted or inactive object
111111z       fixed timestamp
/             symbol table
r             repeater symbol
438.462MHz    frequency in comment
T127          wide FM, opens with 127 Hz tone
C127          wide FM, opens with 127 Hz tone and transmits tone
t127          narrow FM, opens with 127 Hz tone
c127          narrow FM, opens with 127 Hz tone and transmits tone
-760          shift -7.6 MHz
-060          shift -600 kHz
R10k          range 10 km
R15m          range 15 miles