E1820 External Antenna Connector

Since I got my Whooosh back recently, I've been meaning to compare connecting the inductive coupler and pigtail connector on the E1820 again. I figured there would be little point in doing so while my local BTS has been struggling since January 1.

I have a Poynting LPDA-A0044 aimed roughly at tower 4054. For all the tests below I selected the Johannesburg Vodacom speedtest server and the modem was set to 900MHz only.

Results with firmware 11.865.07.00.618:
Antenna CouplingRSSICellIDDownloadUploadPingResults
Inductive-69dBm405418.701.72104link
None-85dBm405412.401.6098link
Pigtail-85dBm405418.701.7197link
Results with firmware 11.831.03.00.00:
Antenna CouplingRSSICellIDDownloadUploadPingResults
Inductive-69dBm405419.291.72112link
None-85dBm405411.400.65111link
Pigtail-85dBm405417.681.34101link
From these results I conclude that the antenna connector on the E1820 does improve upload and download speeds @ 900MHz, even though the modem only reports the internal antenna's signal strength. One would need to use an inductive coupler to aim the antenna initially though.

Unfortunately I am currently unable to connect to the 2100MHz cell (40544), not sure if it's off again or the rain is affecting the signal.
 
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I am situated approximately equal distances from tower 4054 and 4317. My desktop PC faces a window roughly in the direction of tower 4317. If I plug the modem into a front USB port with no antenna, it will constantly switch between cell ID 40541 and 43171. Depending on where I stand, I can force it to one or the other.

I repeated the tests, this time forcing the modem to cell ID 43171, while the antenna remains aimed at 40541.

Results with firmware 11.831.03.00.00:
Antenna CouplingRSSICellIDDownloadUploadPingResults
None-89dBm431712.040.90118link
Pigtail-89dBm431712.011.69115link
Pigtail-89dBm431712.961.7090link
Pigtail-89dBm431713.041.4992link
From previous results posted in this thread, I expected this. If the internal antenna and external antenna do not "see" the same cell there is very little improvement.

Results with firmware 11.865.07.00.618:
Antenna CouplingRSSICellIDDownloadUploadPingResults
None-89dBm431712.261.72100link
Pigtail-89dBm431717.501.70109link
Pigtail-89dBm431718.021.07100link
Pigtail-89dBm431719.761.67107link

I was completely surprised by this result. I even switched back to the 11.831.03.00.00 firmware to confirm that these results were repeatable. It appears that using the MIMO firmware, while still not reporting the signal strength from the external antenna connector, allows the internal and external antennae to attach to different cells.
 
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ginggs said:
If the internal antenna and external antenna do not "see" the same cell there is very little improvement.
Click to expand...

That is shocking. The designer of this modem should be shot.

My friend who lives down the street, has a metal roof. Very little signal comes into his house. He has an external antenna on his roof. After much begging, Cell C sort of gave us tower locations. His modem inside the house however switches regularly between towers. So based on the analysis of ginggs, we can conclude that his external antenna is useless, except when his modem and external antenna happen to "see" the same tower.

I will say it again, shame on you Cell C for releasing this crappy modem.
 
ajax said:
My friend who lives down the street, has a metal roof. Very little signal comes into his house. He has an external antenna on his roof. After much begging, Cell C sort of gave us tower locations. His modem inside the house however switches regularly between towers.
Click to expand...
He should get an inductive coupler.
 
ajax said:
True, but tell him that after spending almost a thousand on an antenna and pigtail.
Click to expand...
See if the MIMO firmware helps, but I will definitely be advising people who don't already have a pigtail to go for the inductive coupler instead.
ajax said:
In addition, the coupler has a couple of dB's loss - not desirable when you need every dB you can get.
Click to expand...
There's definitely a loss in signal strength, but in my case, there doesn't seem to be much of a difference in speed between using the inductive coupler or the pigtail.
 
ajax said:
That is shocking. The designer of this modem should be shot.

My friend who lives down the street, has a metal roof. Very little signal comes into his house. He has an external antenna on his roof. After much begging, Cell C sort of gave us tower locations. His modem inside the house however switches regularly between towers. So based on the analysis of ginggs, we can conclude that his external antenna is useless, except when his modem and external antenna happen to "see" the same tower.

I will say it again, shame on you Cell C for releasing this crappy modem.
Click to expand...

That's because as copy-pastaed in previous threads, the modem uses the external for MIMO (a.k.a. receive diversity). MIMO is per tower only, 'MIMO' across multiple towers would be called dual-cell operation.
 
UnUnOctium said:
That's because as copy-pastaed in previous threads, the modem uses the external for MIMO (a.k.a. receive diversity). MIMO is per tower only, 'MIMO' across multiple towers would be called dual-cell operation.
Click to expand...
It is still MIMO, isn't? MIMO-less firmware do not work, MIMO capable firmware works. Just educated guess...
BTW, MIMO is MIMO, and receive dirersity is not MIMO. MIMO uses diversity channels for its operation, it is why it looks the same things.
 
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Unless its just coincidence i seem to be getting better signal strength/download speeds with that .865 firmware - using inductive coupler.
Only put it on last night but seems stable thus far
 
sajunky said:
It is still MIMO, isn't? MIMO-less firmware do not work, MIMO capable firmware works. Just educated guess...
BTW, MIMO is MIMO, and receive dirersity is not MIMO. MIMO uses diversity channels for its operation, it is why it looks the same things.
Click to expand...

LOL. SIMO and MIMO are both 'receive diversity' (the Multiple Output part). MISO and MIMO are both 'transmit diversity' (the Multiple Input part). For simplicity reasons we'll assume they use MIMO and not SIMO. There's several ways which this provides diversity, to mention:

Spatial [1st antenna transmits to user A, 2nd antenna transmits to user B; all at the same time], usually defined as spatial multiplexing.

Space-time coding [parallel streams are transmitted at the same time to the same user through different antennae. These are precoded using orthogonal codes, the Alamouti code being the most efficient {2x2}], usually known as 'diversity'.

Beamforming [transmitting the same waveforms with adjusted phase and gain such that they arrive at the receiver at the point of maximum constructive interference to maximise SNR], usually known as 'precoding'.

Now, MIMO by definition is an antenna-based scheme and therefore is per base-station. Using multiple base-stations to transmit to the same receiver is called dual cell reception. Think of it as 'MIMO' but extended to multiple base-stations.

Will that be all? :)

Tun@ said:
Unless its just coincidence i seem to be getting better signal strength/download speeds with that .865 firmware - using inductive coupler.
Only put it on last night but seems stable thus far
Click to expand...

The inductive coupler does exactly that. It inductively couples the received signal at the antenna to the PCB traces in the modem. Me and ginggs already deduced through simple elimination that the reported RSSI measured by the uC is that at the primary antenna only. This also explains why they label the external for 'receive diversity only' as it doesn't switch over to it should the BTS not support MIMO, even when the external has a better RSSI.

Now since the internal antenna is actually a PCB trace of specific shape and width, the coupler affects that, that's why a coupler will increase your reported RSSI whereas attaching an external will only increase your throughput.
 
Tun@ said:
Unless its just coincidence i seem to be getting better signal strength/download speeds with that .865 firmware - using inductive coupler.
Only put it on last night but seems stable thus far
Click to expand...

Where did you get the firmware?
 
UnUnOctium said:
The inductive coupler does exactly that. It inductively couples the received signal at the antenna to the PCB traces in the modem. Me and ginggs already deduced through simple elimination that the reported RSSI measured by the uC is that at the primary antenna only. This also explains why they label the external for 'receive diversity only' as it doesn't switch over to it should the BTS not support MIMO, even when the external has a better RSSI.

Now since the internal antenna is actually a PCB trace of specific shape and width, the coupler affects that, that's why a coupler will increase your reported RSSI whereas attaching an external will only increase your throughput.
Click to expand...

BTS is this modem related or network hardware related?
I was using the inductive coupler before on the .831 firmware & lately lucky to see anything over 1Mbps - now on the .865 firmware i'm seeing speedtests returning 2-3Mbps - i have the feeling because of better signal strength with the newer firmware
 
Tun@ said:
BTS is this modem related or network hardware related?
I was using the inductive coupler before on the .831 firmware & lately lucky to see anything over 1Mbps - now on the .865 firmware i'm seeing speedtests returning 2-3Mbps - i have the feeling because of better signal strength with the newer firmware
Click to expand...

Don't know what changes have been done, can't tell you. Could be just a fluke or some crucial processing bug addressed.
 
Before anyone else tries it - Don't bother trying the E182e .868 firmware - it goes on but must only be for t-mobile freq's as the stick don't get signal with that firmware version.
 
Since ginggs has borrowed my Sierra modem, and because I was feeling quite brave after a good lunch and a few alcoholic beverages, I decided to experiment with my E1820 modem to see if I could get it to work better.

I updated the firmware to 11.865.07.00.618. I didn't notice any performance improvements, BUT it didn't seem to want to work on 2100 MHz anymore. I used the MDMA instruction to force a 2100 MHz connection only, but then it wouldn't work at all.

So I went back to 11.831.03.00.00 (luckily I knew about the flash password requirement), and then both the 900 MHz and 2100 MHz bands worked properly again as before.

I have always use my E1820 with an inductive coupler to an external antenna. But I have a second external antenna, so with the inductive coupler still in place, I connected my second antenna to the external antenna connector. Now with two high gain external antennas connected to my E1820, I seem to be seeing 25% faster downloads. Or maybe I should sober up first and check again before I make such a bold statement.

EDIT: The antennas are directional and point to the same tower.
 
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