Call Search
     

New to Ham Radio?
My Profile

Community
Articles
Forums
News
Reviews
Friends Remembered
Strays
Survey Question

Operating
Contesting
DX Cluster Spots
Propagation

Resources
Calendar
Classifieds
Ham Exams
Ham Links
List Archives
News Articles
Product Reviews
QSL Managers

Site Info
eHam Help (FAQ)
Support the site
The eHam Team
Advertising Info
Vision Statement
About eHam.net

   Home   Help Search  
Pages: [1]   Go Down
  Print  
Author Topic: Why would a repeater have a DCS output tone?  (Read 4991 times)
KC9RCG
Member

Posts: 142




Ignore
« on: March 21, 2011, 10:42:39 AM »

We have several repeaters in our area. However, one has a pl input tone...that I understand. However, what might be the purpose of a DCS output tone?

thanks
Logged
VA3WXM
Member

Posts: 277




Ignore
« Reply #1 on: March 22, 2011, 08:28:20 AM »

Same reason some repeaters have a PL output tone: to keep a user's radio quiet until a signal WITH the proper tone is received.

DCS (or DPL) is just a fancier way of doing it.
Logged
K9MHZ
Member

Posts: 439




Ignore
« Reply #2 on: March 22, 2011, 11:57:46 AM »

It's very common with biz band radios.  Also, the microphone in its hanger will activate the function in the radio itself, ie. mic in hanger.....radio only opens up when it receives a DPL burst, mic out of hanger....radio receives everything on that freq.

Logged
N1OFJ
Member

Posts: 18




Ignore
« Reply #3 on: March 23, 2011, 12:24:24 PM »

Why use a DCS output code.  We use one on our 440 repeater...and here is why:  Elimination of squelch crashes when the repeater transmitter unkeys.  With regular analogue PL..(our repeater is a Motorola), the only radios to have no squelch crash would be a Motorola mobile or portable.  Amateur rigs or other manufacturers do not understand Motorola "reverse burst" or PL phase reversal timing...hence the squelch crash.  With DCS, since a turn-off code is sent, it does not matter which rig you are using (provided it has a DCS decoder)...you get no squelch crash when the transmitter unkeys.
Logged
VA3WXM
Member

Posts: 277




Ignore
« Reply #4 on: March 24, 2011, 11:57:24 AM »

I hadn't thought of the squelch crash issue.

My club's repeaters are GE Mastr II's that transmit a PL tone and I get squelch crashes on my Yaesu radios (FT-8900 and VX-7R) but not on any of my Kenwood radios (TM-V71A, TK-790, TK-890, TS-2000, TH-D7A, TK-290 and TK-390).  Not sure why that is.
Logged
N1OFJ
Member

Posts: 18




Ignore
« Reply #5 on: March 24, 2011, 12:16:01 PM »

If your Mastr II's are using the original GE PL encoders, the PL reverse burst (which utilizes a 180 degree phase reversal in 150 milliseconds) would match what Kenwood used for their commercial radios, therefore no squelch crash...it is possible (not sure as I do not own Kenwood equipment) that Kenwood has incorporated it's commercial PL encoding/decoding into their amateur line.  Motorola utilizes a 120 degree phase reversal in 180 milliseconds.
Logged
VA3WXM
Member

Posts: 277




Ignore
« Reply #6 on: March 25, 2011, 06:29:52 AM »

Thanks for the explanation.  I believe the repeaters are using GE PL encoders.
Logged
KV4BL
Member

Posts: 78




Ignore
« Reply #7 on: March 25, 2011, 07:04:35 AM »

How cool that the owner or trustee encodes the output at all!!!!   I find it sad, the number of repeaters which require a tone for access but which do not encode a tone on the output.   To me, such is frequently the case of poor or slovenly engineering by the owner/trustee.   In many if not most cases these days, encoding a PL only requires some programming which could have been done while programming a tone requirement on the input.  In some cases, expensive or hard to find reeds or other parts may be the stumbling block to PLing the output and that is understandable.   Others find some of the lamest excuses for not PLing the outputs.  "The tone causes distortion."   "We had complaints from users of a distant repeater that our users were unaware they were keying up their (un-PL'd) repeater during band openings."   "Why would you need a tone on the output?"  Another is, "well, the machine passes PL tones". 

As for distortion caused by PL on the output, I was under the impression that we used communications grade equipment to communicate, NOT for high-fidelity programming.   If the users of a distant repeater are frustrated by the users of your machine keying it up during band openings, maybe it is well past time that they shook hands with fifty plus year-old technology commonly known as PL.  Contrary to apparent beliefs, CTCSS or PL is not some evil combination of Witchcraft and nuclear science which will end mankind if mishandled.  It is old and proven technology which allows people to monitor a frequency without their squelch constantly breaking from spurs, intermod, computer noise, automobile components, or other sources.  DPL has been around at least since the 70's.  NEWS FLASH:  Passing PL tones, contrary to popular belief, is NOT the same or as good as PLing the output.  I have yet to hear a machine that only "passes tones", which will reliably activate the decoder on all radios for each and every user whose tone is being supposedly "passed".  Most machines which only pass PL tones will produce a hodgepodge of broken transmissions, some coming in great, and others not opening your decoder at all.  In other words, USELESS.   One repeater I am familiar with which has been well-used and one of the few successful carrier-squelch machines in the area recently had to PL its input due to some noise source on its input.   I had hoped that the output was going to be also PL'd, but it wasn't.  On two radios of mine, an Icom 746-Pro and a 2820, the passed tones work perfectly and so far, without a hiccup, which is very unusual.  On my VX-3R, the passed tones absolutely will not open the decoder.

The best engineered repeaters (and sadly, the most uncommon) are the ones which only encode a tone on the output when a user actually has his radio keyed.   That way, Morse ID's, voice announcements, and other noise from the machine do not unnecessarily disturb you while you work, watch TV, or try and snooze.   People are more likely to monitor it for emergency calls or other traffic if they are not bothered by all that noise.

Rant off.  :-)

73,

Ray  KV4BL
Logged
N1OFJ
Member

Posts: 18




Ignore
« Reply #8 on: March 26, 2011, 10:49:17 AM »

Ray, how true it is on some of the poor practices.  repeaters should decode and encode separately.  This way here...any decent repeater should be utiliizing high pass filtering (pass above 300 Hz)  on receive audio to eliminate any low frequency stuff.(PL, DCS, etc.) before delivering the audio to the transmitter.  The transmitter should be encoding standalone, not passing user PL, DPL etc.  That passing stuff is very inconsistant and quite frankly sounds horrible.  I am surprised on some of the reasoning some repeater operators do not utilize PL/DPL. Most modern transceivers today come with both encode/decode features, and it is easy to encode on the presence of incoming logic only. 
Logged
K5LXP
Member

Posts: 4522


WWW

Ignore
« Reply #9 on: March 27, 2011, 08:06:43 AM »

Another reason you might want to use DCS on the output is for linking purposes.  A remote receiver would only respond to that exact code and would offer some degree of uniqueness, since most ham gear can't generate commercial DCS codes.

What I did with my repeater was to use a programmable encoder (tone PL) so that depending on the state of the repeater, the output code is different.  There is one tone when receiving on the input, and other tones when receiving via the link, the remote base, or when the autopatch is active.  That way you can program your receiver to only receive the activity you're interested in, or CSQ to hear everything. 

As far as the squelch crash the best way to deal with that is to cut the tone at the loss of signal, rather than at the end of the squelch tail.  Not only does that eliminate the crash, but it gives users the option of keying cross band repeaters off the tone rather than the tail, so they don't have to wait for the repeater to drop before they can transmit.


Mark K5LXP
Albuquerque, NM
Logged
Pages: [1]   Go Up
  Print  
 
Jump to:  

Powered by MySQL Powered by PHP Powered by SMF 1.1.11 | SMF © 2006-2009, Simple Machines LLC Valid XHTML 1.0! Valid CSS!