Improving reception for HSDPA modem Sierra Wireless MC8775
Posted: Sat Jul 02, 2011 3:39 am
I have recently bought a Lenovo X61 Tablet with inside a HSDPA modem (PCI-E), a Sierra Wireless MC 8775.
The modem is located inside the case, just below the palmrest, in a PCI-Express slot.
From the start I had sensitivity issues, i.e. the 3G operators are seen very very weakly (while my phone sees tham at 5 ticks, i.e. full strenght), so the connections either are not possible or start and go away after seconds....
I thought it was a firmware problem (and even had a problem with flashing it, but at the end was able to debrick it...), but after opening the case I discovered that the modem was simply connected to a small square antenna with a cable of around exactly 5 cm like this:
http://i.ebayimg.com/20/!B98bUHw!mk~$%2 ... ~~0_12.JPG
I disconneted this antenna and connected the second antenna from the WLAN (the one connected to TR2 in the WLAN card) which I believe is going in the back of the monitor and should bring in more useful signal.
This improved the situation, but I am still very very far from what I have in any phone and the line is almost not usable at all.
Can anyone suggest what can be done/measured (maybe via the AT commands) to check the situation and improve the HSDPA reception?
The modem is located inside the case, just below the palmrest, in a PCI-Express slot.
From the start I had sensitivity issues, i.e. the 3G operators are seen very very weakly (while my phone sees tham at 5 ticks, i.e. full strenght), so the connections either are not possible or start and go away after seconds....
I thought it was a firmware problem (and even had a problem with flashing it, but at the end was able to debrick it...), but after opening the case I discovered that the modem was simply connected to a small square antenna with a cable of around exactly 5 cm like this:
http://i.ebayimg.com/20/!B98bUHw!mk~$%2 ... ~~0_12.JPG
I disconneted this antenna and connected the second antenna from the WLAN (the one connected to TR2 in the WLAN card) which I believe is going in the back of the monitor and should bring in more useful signal.
This improved the situation, but I am still very very far from what I have in any phone and the line is almost not usable at all.
Can anyone suggest what can be done/measured (maybe via the AT commands) to check the situation and improve the HSDPA reception?