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New XPR7550e - 8% better range - is this true?

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g8tzl2004
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New XPR7550e - 8% better range - is this true?

Postby g8tzl2004 » Tue Sep 19, 2017 3:25 pm

I read that the "new" XPR7550e (note the "e") vs the original XPR7550 had a quoted 8% better range compared to the original XPR7550.

The official spec says the XPR7550e has an RX sensitivity of 0.16uV (analog) for 12dB SINAD and 0.14uV (digital).

The original XPR7550 had quoted "typical" specs of 0.22uV for 12dB SINAD.

BUT the original XPR7550 has an exceptionally sensitive front end...much better than 0.22uV and probably around 0.14uV.

So has the RX sensitivity of the XPR7550e actually improved or has Motorola just (for once) provided a true measure of the actual sensitivity rather than using the useless default specs of 0.22uV for 12dB SINAD which it uses on lots of radios?? So in reality is there actually NO RX sensitivity difference between an XPR7550e and an XPR7550?

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Bill_G
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Re: New XPR7550e - 8% better range - is this true?

Postby Bill_G » Tue Sep 19, 2017 6:42 pm

I think it reflects greater confidence in their stated guaranteed performance rather than an actual change in performance. That is, the 7550's have hot front ends, but had an understated receiver spec that they could guarantee. But now, after years of excellent production runs, they are confident they can guarantee these better numbers. So, nothing has changed except their confidence.

N4KVE
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What radios do you own?: XTS3000/5000, TRBO, 900MHZ

Re: New XPR7550e - 8% better range - is this true?

Postby N4KVE » Wed Sep 20, 2017 7:22 am

I never read that. But I did read that the "e" has better battery life. GARY

g8tzl2004
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Re: New XPR7550e - 8% better range - is this true?

Postby g8tzl2004 » Fri Sep 22, 2017 5:21 am

The 8% improved range claim is in official Motorola specs "....an improved receiver boosts range by up to 8%".

Its interesting that Motorola has actually published accurate sensitivity specs...it will be interesting to see if all the new dual band P25 stuff has similar official accurate Rx sensitivity measurements.

I would also be interested to establish how Motorola actually worked out that the increased coverage was "up to 8%"...is there a formula or did they carry out trials?

I still don't know why the "sister" XPR5550 mobile does not have a similar hot receiver. I also recently checked out a Vertex VXD7200 (XPR4550 clone) and that had the same sensitivity as the XPR5550.

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Bill_G
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Re: New XPR7550e - 8% better range - is this true?

Postby Bill_G » Fri Sep 22, 2017 7:36 am

There is no direct correlation between rcvr sensitivity and range. It is merely one of many things to consider. And quite often, sensitivity comes at the cost of rejection.

My RL experience with a UHF 7550 is it performs better than previous HT models in a number of situations. It truly does have some good ears, and doesn't turn to garbage at a high site with thousands of watts floating in the air.

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escomm
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Re: New XPR7550e - 8% better range - is this true?

Postby escomm » Fri Sep 22, 2017 7:53 am

I have a customer with a spot that is very fringy... legacy and E models both key into the repeater but do not pass any audio... I would like to see some proof of these claims... range is a two way street...

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Bill_G
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Re: New XPR7550e - 8% better range - is this true?

Postby Bill_G » Fri Sep 22, 2017 8:54 am

Yep. There's uplink and downlink range, and differences of antenna elevations, antenna patterns, site noise, clutter density, et al to consider.

But, sales people love incremental improvements.

g8tzl2004
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Re: New XPR7550e - 8% better range - is this true?

Postby g8tzl2004 » Fri Sep 22, 2017 9:55 am

The default squelch on the DMR repeater might be too high...and there is probably nothing you can do to lower it?

The lowest analog SQ setting on my XPR5550 is also too high...there are only 2 SQ levels rather than being fully adjustable (such as with an MCS2000)....and its maybe the same in DMR mode.

The green LED lights up on a weak copyable analog signal but the SQ does not open...but if you manually open the SQ you can hear the signal OK. But you need an extra 2dB of signal for the SQ to automatically open. Motorola need to change the firmware so that you can lower the SQ to whatever level you want rather than just having 2 levels...especially as the green LED lights up so you know the radio is receiving a signal but the SQ is not opening.

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Bill_G
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Re: New XPR7550e - 8% better range - is this true?

Postby Bill_G » Sat Sep 23, 2017 4:07 am

Ah yes - It's the AND/OR SQ debate again this time in digital. Which is better.

Threashold squelch and usable signal are two different things. The radio may be able to decode the envelope enough to trigger a detect, but not well enough to open the audio gate. 2db may be all it takes, but it is your visual indicator of your existing signal conditions. Use it as a tool.

g8tzl2004
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Re: New XPR7550e - 8% better range - is this true?

Postby g8tzl2004 » Sat Sep 23, 2017 2:37 pm

When the green RX LED lights up, I want the SQ to open!!!!

Once the green LED lights up, the signal is readable BUT the radio then requires an extra 2dB of signal to open the SQ.

What's the point of having the green LED light up if the SQ will not open?

Why only have 2 SQ levels....why not have a variable SQ level so I can set the SQ at whatever threshold I want....like with every previous Motorola analog and P25 radio?

Who at Motorola decided that 2 SQ levels was good enough?

Also my UHF XPR7550 SQ does open on a just readable signal...but not my XPR5550 and XPR3500...go figure. Have later firmware updates increased the SQ threshold as commercial users complained that the radio opens on too weak signals :)?

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Bill_G
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Re: New XPR7550e - 8% better range - is this true?

Postby Bill_G » Sat Sep 23, 2017 8:33 pm

Do you need a kleenex with aloe, or will any tissue do? :)

g8tzl2004
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Re: New XPR7550e - 8% better range - is this true?

Postby g8tzl2004 » Sun Sep 24, 2017 7:15 am

Aloe will be nice...thank you :)

g8tzl2004
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Re: New XPR7550e - 8% better range - is this true?

Postby g8tzl2004 » Sun Sep 24, 2017 7:28 am

I need to do some experimenting...but can you not use Service Mode (or whatever) to lower the SQ threshold level - presumably the level of the 2 default SQ settings (normal/tight) must be set somehow?


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