[amsat-bb] Why 6 digit grid locator in Europe?

Edward R Cole kl7uw at acsalaska.net
Fri Feb 19 22:34:54 UTC 2016

Note: that I read the digest of amsat-bb and normally only scan it 
lightly, so coming into this in mid-thread:

I primarily work eme (144 since 1998 and 1296 only a couple 
years).  So haven't done much satellite since demise of AO-40 (still 
getting system restored).  I use JT65 on 2m-eme but not on HF so my 
experience is with on eme.

4-digit grid square was chosen by Joe Taylor-K1JT when writing JT65 
as info traded in the contact as signal level is calculated and 
displayed by the program in dB below SNR=0 for a 2.5 KHz bw (std SSB 
bw). Therefore a signal report would be duplicative to the sw 
display. Eme hams do generally exchange signal level received when 
running digital modes but this manually added into the "73" report or 
included in QSL's.

On CW-eme the TMO system is not used unless signals are very weak; 
most now just send RST via CW.  TMO is used at "432 and up" while a 
shorter system of O/RO/RRR is used on 222 and down.  JT65 is set up 
to send this report system.

For terrestrial VHF contests (US) only 4-digit grid is exchanged.

But most eme stations display and exchange 6-digit grids on QSL's and 
for more precise station location when using eme tracking programs.

73, Ed - KL7UW
144-eme: 4x XP-20 + 1300W
1296-eme: 4.9m dish + 125w
sat: 7-elem 2m yagi, 26-elem 435 x-yagi, patch for 2.4 GHz.

Date: Fri, 19 Feb 2016 18:31:27 +0100
From: Dani EA4GPZ <daniel at destevez.net>
To: "amsat-bb at amsat.org" <amsat-bb at amsat.org>
Subject: Re: [amsat-bb] Why 6 digit grid locator in Europe?
Message-ID: <56C7516F.8090404 at destevez.net>
Content-Type: text/plain; charset=utf-8

El 18/02/16 a las 23:06, Peter Goodhall escribi?:

 > But I honestly don't feel that because on EME or M/S its just 4
 > characters that it should mean a sudden switch, for EME/MS ...
 >... which has
 > moved into HF with JT65 and JT9 before then apart from in a PSK brag
 > file you never really heard QRAs on HF.

In fact it's not the case that they use 4 digit locators on EME. 4 digit
locators are used in many JT modes just because there are some spare
bits in the message format.

I think that operators EME CW don't send locators ever. They have their
own signal report system called TMO, where they send one of the letters
T, M or O three times based on the amount of data they could copy.


For MS there is signal report system based on the length an strength of
the pings.


The thing is that in the US 4 digit locators are normally used for
terrestrial VHF and such instead of 6 digit locators. In fact, 6 digit
locators are almost unheard of and many operators won't know their 6
digit locator. I read recently a proposal of change to the rules of the
IARU R1 50MHz contest regarding this matter. This contest currently
requires that 6 digit locators are exchanged over the air. However,
there is a problem that US operators will usually pass just 4 digit
locators and it's difficult explain and get their 6 digit locator under
marginal propagation conditions (the usual conditions in transatlantic

 > I'm not sure how long the 6 characters has been a thing on the
 > satellites in Europe, but in the 4 years I've been on it's certainly
 > that its easily 50% of the time lost just to people probably not being
 > able to hear the satellite in the first place.

I don't know either, but it's only the case in Europe. In the US they
normally use 4 digit locators on satellites. I think that the difference
in use comes from terrestrial VHF.

The thing is that perhaps we as a community of satellite operators
should decide what do we consider as a signal report or valid contact.
As you said, the standard signal report doesn't make much sense for
satellites. The report could be the locator, but I don't think this is
such a good idea because it is not so easy to copy a 6 digit locator in
poor conditions (in Europe the many different accents and languages
don't help either). The report should be easier to copy.

I agree that in good conditions you can send back and forth 6 digit
locators real quick. However, in poor conditions, if you want to get
them copied properly, you will probably have to repeat it several times
and perhaps request a readback.

The problem with any idea about changing the established customs is that
the satellite community is quite big and spread out. Most of the
operators don't read amsat-bb. By comparison, the EME and MS communities
are smaller and the guys there tend to frequent the same mailing lists
and webs for skeds.

 > Just my thoughts anyway and many thanks for the squares while you've
 > been on from the UK.

Could you get IO95? I hear that's quite a rare grid.


Dani EA4GPZ.

73, Ed - KL7UW
     "Kits made by KL7UW"
Dubus Mag business:
     dubususa at gmail.com

More information about the AMSAT-BB mailing list