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Author Topic: Repeater Question  (Read 245 times)

K0ABD

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    • RichEssence
Repeater Question
« on: December 02, 2019, 09:19:24 AM »

Hi Folks,

New Ham. I got my ticket last March & decided to focus on other things. Recently I've been looking to get back into it. So, my question here might be a bit basic.

I have a Baofeng BF8HP & I'm looking to connect to nearby 2-meter repeaters. Checking out Massachusetts repeaters on https://www.repeaterbook.com/repeaters/Display_SS.php?state_id=25&band=14&loc=%&call=%&use=% I find some are D-STAR. I realize that I need a D-STAR radio to connect to these.

However, when I click on these repeaters I see "D-STAR Enabled" with Uplink, Downlink, & Offset frequencies. Does this mean these repeaters are both FM/VHF & digital? Or are they exclusively digital?

Also, from what I understand, with my rig I can link to AllStar, EchoLink, IRLP, & IDAS (NXDN) repeaters. Sound right?

When I select the CC repeaters I see they are "DMR Enabled" & have Uplink, Downlink, & Offset frequencies. Again, is this exclusively DMR or are these also VHF?

Thank you,

Mark/K0ABD
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N2AYM

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Re: Repeater Question
« Reply #1 on: December 02, 2019, 10:23:53 AM »

Mark - you seem a little confused.
DMR, DStar, IDAS and NXDN are digital modes. FM is analog mode.
VHF is a frequency range. I doubt your baofeng is going to work
on Star, IDAS, NXDN but if your baofeng is properly configured it
may work on DMR if it is equipped to do so. First you have to have
the input and output frequencies properly programmed in your radios
memory locations that you have them programmed into.
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KR6NU

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Re: Repeater Question
« Reply #2 on: December 02, 2019, 10:36:39 AM »

I've never used the BF8HP. but according to the manufacturer specs it's strictly an analog FM transceiver so you won't be able to use it on any digital repeaters, be they DMR, D-Star, C4FM or whatever.  You might want to consult the New England Repeater Coordination Council website (nesmc.org) for repeater info.  Their database is likely more current than that repeater handbook.
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K5LXP

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Re: Repeater Question
« Reply #3 on: December 02, 2019, 11:54:11 AM »

Actually, they just might  be multimode.  My DMR repeater using an MMDVM modem supports both digital and FM analog (not at the same time).  Listings don't always show whether a machine is multimode.  So the answer is you *might* find a digital system that's compatible with FM, but you would need to find that information either at the sponsor's site or from someone that knows the system.

QRZ shows you just north of Boston.  From my recollection when I lived in MA there is no shortage of FM repeaters around you.

Mark K5LXP
Albuquerque, NM
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K0ABD

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    • RichEssence
Re: Repeater Question
« Reply #4 on: December 02, 2019, 12:11:40 PM »

KR6NU & K5LXP, thanks for the responses.

When I select the CC (DMR) & DSTR repeaters, I see those digital modes are "enabled," that I interpreted as supporting digital, yet not exclusively a digital repeater.

Those same repeaters have 2-meter Uplink & Downlink frequencies.

That caused me to wonder if they were multimode, also supporting VHF.

Mark
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K5LXP

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Re: Repeater Question
« Reply #5 on: December 03, 2019, 11:41:40 AM »

Seems you're still confusing vernacular.  VHF is a band.  Having separate TX and RX frequencies is an indicator of duplex, a repeater that transmits and receives at the same time irrespective of mode or band of operation.  Any radio made in the last 30 years or so supports duplex, on whatever bands it was made for.  If your radio is VHF you can work duplex repeaters on 2M, the only question here is if the repeaters you want to access support the mode your radio has, which seems to be FM only.

Mark K5LXP
Albuquerque, NM
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KC0MYW

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Re: Repeater Question
« Reply #6 on: December 03, 2019, 03:53:18 PM »

You've gotten some good input and explanations from others, but I'll add another way to look at it that may help. I'll try and give a clear breakdown that will help anyone who may stumble across this thread and be confused, or not have a complete understanding, so for the parts you already understand, just consider them a refresher on what you already know.

Radio Spectrum is divided into bands of frequencies and we typically follow the ITU definition:
https://en.wikipedia.org/wiki/Radio_spectrum#ITU
For amateur radio, the vast majority of activity is in the following 3:
HF: 3-30MHz
VHF: 30-300MHz
UHF: 300-3,000MHz

In amateur radio, we consider different parts of our authorized frequencies as bands and often refer to them by their wavelength. A whole other discussion could be had about wavelengths, but for now just consider that taking 300 divided by the frequency in MHz will give a good approximation of the wavelength in meters. There are many resources to find the amateur radio allocations, for example: http://www.arrl.org/files/file/Regulatory/Band%20Chart/Band%20Chart%208_5%20X%2011%20Color.pdf

For illustration, some of the US amateur bands are:
40 meters: 7.000-7.300MHz
20 meters: 14.000-14.350MHz
10 meters: 28.000-29.700MHz
6 meters: 50.000-54.000MHz
2 meters: 144.000-148.000MHz
70 centimeters: 420.000-450.000MHz

In this case, the radio is a dual-band radio capable of operating in VHF and UHF frequency ranges. But the only covered US amateur bands are 2 meters and 70 centimeters.

Take a repeater with uplink/downlink frequencies that fall within the specified range, and all should be good....ALMOST!

The next item to consider is the mode that will be used on that frequency to transmit and receive information. Modes typically refer to the modulation type and operating protocols. In amateur radio, some of the commonly used modes are:
CW
AM
FM
SSB (USB/LSB)
P25
DSTAR
DMR
C4FM
SSTV

As a side note, there are some modes (FT8, APRS, PSK31, and others) that insert audio into the microphone input of a radio and use an analog mode such as SSB, AM, FM, etc to transmit the communication.

In this case, the radio is only capable of FM. Even if another radio were on the same frequency but transmitting in one of the other modes, communication would not be had. For example, this radio can tune to the frequency of a DSTAR only repeater in the 2 meter band but not communicate with it.

Now, some "digital enabled" repeaters for C4FM or DSTAR or DMR are in fact multi-mode repeaters that support both analog FM and whichever digital mode is enabled (as in the example K5LXP gave) while others are strictly digital or strictly analog. You will have to either experiment or get information from the repeater sponsor (information is often found on club websites) or another area ham.

Beyond this, there is one more step that gets added into the confusion as well.

After programming in the correct frequencies and verifying the correct mode, the next step would be to link multiple repeaters together as is often done. There are several ways to do this and many of the linking methods are independent of the mode selection. Historically, the main ways to link repeaters was via dedicated phone lines and RF links, now we also have internet based methods:
AllStar
EchoLink
IRLP

In this case, as long as the repeater uses FM as the mode on the RF side, it would be able to use whatever linking method the repeater has. However, if the repeater uses a different mode (such as DSTAR) on the RF side, the radio would not be able to use it whether it is linked or not and no matter what linking mode is used.

Hopefully this is a useful explanation that clears some things up, and perhaps will help someone else along the way as well.
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