How much of an effect does the cable choice have on the signal strength

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tonydobbs
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How much of an effect does the cable choice have on the signal strength

Post by tonydobbs » Sun Feb 10, 2019 1:58 pm

I'm trying to optimize my LTE setup in the mountains of rural CA, and I'm running into an issue. I mounted this 8db antenna outside my window (~20feet above ground) with mostly unobstructed LoS (2 small mostly dead trees about 50 and 100 feet out). Shockingly my signal strength seems worse than with the 2 omni's that came with the device. I've adjusted the antenna every way that I could think of, and now I'm wondering if the issue might be with the cables I selected. I'm using this cable which is only 6.5ft. Is it possible that my cable selection is the issue? If it's unlikely to be the cable, I suppose the next step is to try other antennas and consider picking up more testing equipment.

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JimHelms
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Re: How much of an effect does the cable choice have on the signal strength

Post by JimHelms » Sun Feb 10, 2019 5:38 pm

It is easy to lose more thru cable loss than is otherwise gained from an external antenna.

With that said, I would not think you would lose a lot at 6.5 feet.
Loss per foot (per 30 cm) at 900 MHz: 0.14 dB
Loss per foot (per 30 cm) at 2500 MHz: 0.24 dB
RG58 cable is best suited for applications below the 2.5GHz (2500HMz) frequency.

What router, firmware, modem, and carrier are you using?

tonydobbs
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Re: How much of an effect does the cable choice have on the signal strength

Post by tonydobbs » Sun Feb 10, 2019 6:00 pm

I'm using a WE826-T2 + MC7455 from you guys with the R00ter firmware on ATT band B2. I had another thought... my antenna is attached to my house instead of a pole, so the grounding strap isn't attached, could that be the issue?

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JimHelms
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Re: How much of an effect does the cable choice have on the signal strength

Post by JimHelms » Sun Feb 10, 2019 6:13 pm

The ground wire does not make a difference in its reception. It is to ground the antenna to the ground to help protect during a lightning strike.

Is the antenna pointed directly at the tower. Those antennas are very directional and, much like a satellite dish, a little off aim can have a profound affect on signals, completely missing the tower.

What does it look like when you run the AT Command:

Code: Select all

AT!GSTATUS?

tonydobbs
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Re: How much of an effect does the cable choice have on the signal strength

Post by tonydobbs » Sun Feb 10, 2019 6:23 pm

I'm thinking it must not be aimed well enough. I only know generally where the tower is, so I aimed it by recording the signal strength 3 times, moving it 2 degrees, and repeating the process.

Here is the current status (not too bad currently)

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Current Time:  18260		Temperature: 43
Reset Counter: 1		Mode:        ONLINE         
System mode:   LTE        	PS state:    Attached     
LTE band:      B2     		LTE bw:      20 MHz  
LTE Rx chan:   800		LTE Tx chan: 18800
LTE CA state:  NOT ASSIGNED
EMM state:     Registered     	Normal Service 
RRC state:     RRC Connected  
IMS reg state: No Srv  		
PCC RxM RSSI:  -77		RSRP (dBm):  -106
PCC RxD RSSI:  -78		RSRP (dBm):  -109
Tx Power:      22		TAC:         8B06 (35590)
RSRQ (dB):     -10.0		Cell ID:     0A15ED09 (169209097)
SINR (dB):      9.6
OK
EDIT: I'm not seeing SCC listed... does that mean I'm only connected to the primary?

tonydobbs
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Re: How much of an effect does the cable choice have on the signal strength

Post by tonydobbs » Sun Feb 10, 2019 6:47 pm

So this is interesting... I've been swapping antennas and messing around all day and nothing changed much. Just now I tried seeing how things performed with one SMA plug attached, then the other, then both... Now I'm on B12 with better values, and my speedtest results are much lower than before... But check this out... SCC appears.

Code: Select all

Current Time:  19164		Temperature: 44
Reset Counter: 1		Mode:        ONLINE         
System mode:   LTE        	PS state:    Attached     
LTE band:      B12    		LTE bw:      5 MHz   
LTE Rx chan:   5145		LTE Tx chan: 23145
LTE CA state:  INACTIVE    		LTE Scell band:B2     
LTE Scell bw:20 MHz  		LTE Scell chan:800
EMM state:     Registered     	Normal Service 
RRC state:     RRC Connected  
IMS reg state: No Srv  		
PCC RxM RSSI:  -70		RSRP (dBm):  -96
PCC RxD RSSI:  -67		RSRP (dBm):  -88
SCC RxM RSSI:  -88		RSRP (dBm):  -110
SCC RxD RSSI:  -86		RSRP (dBm):  -110
Tx Power:      0		TAC:         8B06 (35590)
RSRQ (dB):     -11.6		Cell ID:     0A15EA10 (169208336)
SINR (dB):      3.4
OK

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JimHelms
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Re: How much of an effect does the cable choice have on the signal strength

Post by JimHelms » Sun Feb 10, 2019 6:50 pm

Your signal stats are not that bad.

Yes, aiming an antenna can be a tedious process. I prefer to use the screen you reference above for the final tweaking.

Also pay attention to your RxM (main) and the RxD (div) RSRP while you are fine tuning. You want little difference between them.

It is not receiving the Secondary Carrier used for Carrier Aggregation. This could a tower limitation. Have you every noticed the secondary before.

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Re: How much of an effect does the cable choice have on the signal strength

Post by JimHelms » Sun Feb 10, 2019 6:53 pm

Your slower speed is probably due to B12 only being 5MHz where B2 is 20Mhz.

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Re: How much of an effect does the cable choice have on the signal strength

Post by JimHelms » Sun Feb 10, 2019 6:55 pm

And, the tower you are pointed towards, is an AT&T tower?

tonydobbs
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Re: How much of an effect does the cable choice have on the signal strength

Post by tonydobbs » Sun Feb 10, 2019 6:57 pm

JimHelms wrote:
Sun Feb 10, 2019 6:50 pm
Your signal stats are not that bad.
Yea they're not terrible by any means... I just was expecting the directional antenna to perform better than the tiny omnidirectional ones that came with the router.
Yes, aiming an antenna can be a tedious process. I prefer to use the screen you reference above for the final tweaking.
What do you use for your primary aiming? Do you just drive to the towers to confirm which one is for the provider and then use a compass to determine the heading?I had thought about that, but my cell provider is Verizon and my LTE home setup is ATT... I'll have to see if I can pop this SIM into a phone and get readings from that.
Also pay attention to your RxM (main) and the RxD (div) RSRP while you are fine turning. You want little difference between them.
Thanks for the tip!
It is not receiving the Secondary Carrier used for Carrier Aggregation. This could a tower limitation. Have you every noticed the secondary before.
I have, but mostly with the omni's. Now I'm seeing it with my directional, but speeds are down again.. in the 8mbps down territory now.

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