Hello,
Was interested to see how my signal strength changed in the house and thought I would share the few findings.
Firstly I needed to find out what dBm and ASU meant and linking to wiki here http://en.wikipedia.org/wiki/Mobile_phone_signal#Active_Set_Update_Rate
ASU means:
Although the mobile standards define an ASU message ("Active Set Update") used in handover procedures, on Android phones the acronym ASU has nothing to do with Active Set Update. It seems not to be declared precisely by Google developers but probably means "Arbitrary Scale Unit" or "Android Signal Unit". (see NeighboringCellInfo)
It is an integer value proportional to the received signal strength measured by the mobile phone. It is possible to calculate the real signal strength measured in dBm (and hence Watt) by a formula. However, there are different formulas for 2G and 3G networks.
In GSM networks, ASU is equal to the RSSI (received signal strength indicator, see TS 27.007).
dBm = 2*ASU - 113, ASU in the range of 0..31 and 99
In UMTS networks, ASU is equal the RSCP level (received signal control power, see TS 25.125)
dBm = ASU - 116, ASU in the range of -5..91
The dBm explanation was a little more dense http://en.wikipedia.org/wiki/DBm and did not really add much except that in the case of cell phones it is negative number and the closer to 0 it is the stronger it is.
Anyone with more technical knowledge feel free to add in or correct but I am just trying to simplify it and explain it as I understand it.
Looking at the calculation above, even though my handset (Samsung Galaxy S on 3) tells me my Mobile Network Type is HSDPA or UMTS my calculations seem to work using the GSM calculation viz. dBm = 2*ASU - 113
Thus if my ASU is 4 the dBm is (2*4)-113 = -105 which I found strange but reporting the facts.
In my home office, my signal strength varies between 2-6 ASU or -109 to -101 dBw. If I go outside this will boost to about 8/9 ASU or -97 to -95 dBW.
Moving upstairs to the side of the house nearest our closest radio transmitter (Theydon Bois) the ASU went up to 20 with -73 dBm. Logic would dictate that height in the house is better than being outside and behind the house.
As a further test, if I put my one hand in the normal holding position (bottom of handset), the ASU dropped to about 17 (-79 dBm) and if I enclosed the aerial with both hands this dropped to 14 ASU (-85dBm). When I then turned my body to use it to shield the phone from the signal the ASU dropped to 8 (-97dBm).
So, whilst not scientific, if you are seeing a low signal, holding the phone awkwardly at the top buys you another 3ASU which could mean the difference of one or two bar of signal as below.
I found that at 0-2 ASU I had one bar of signal. 3-5 was 2 bars, 6-10 was 3 bars and 11 and over was 4 bars (maximum) signal. I suppose depending on phone make and model YMMV.
Not sure if anyone found that useful or even interesting but thought I would note it down.
NB
Was interested to see how my signal strength changed in the house and thought I would share the few findings.
Firstly I needed to find out what dBm and ASU meant and linking to wiki here http://en.wikipedia.org/wiki/Mobile_phone_signal#Active_Set_Update_Rate
ASU means:
Although the mobile standards define an ASU message ("Active Set Update") used in handover procedures, on Android phones the acronym ASU has nothing to do with Active Set Update. It seems not to be declared precisely by Google developers but probably means "Arbitrary Scale Unit" or "Android Signal Unit". (see NeighboringCellInfo)
It is an integer value proportional to the received signal strength measured by the mobile phone. It is possible to calculate the real signal strength measured in dBm (and hence Watt) by a formula. However, there are different formulas for 2G and 3G networks.
In GSM networks, ASU is equal to the RSSI (received signal strength indicator, see TS 27.007).
dBm = 2*ASU - 113, ASU in the range of 0..31 and 99
In UMTS networks, ASU is equal the RSCP level (received signal control power, see TS 25.125)
dBm = ASU - 116, ASU in the range of -5..91
The dBm explanation was a little more dense http://en.wikipedia.org/wiki/DBm and did not really add much except that in the case of cell phones it is negative number and the closer to 0 it is the stronger it is.
Anyone with more technical knowledge feel free to add in or correct but I am just trying to simplify it and explain it as I understand it.
Looking at the calculation above, even though my handset (Samsung Galaxy S on 3) tells me my Mobile Network Type is HSDPA or UMTS my calculations seem to work using the GSM calculation viz. dBm = 2*ASU - 113
Thus if my ASU is 4 the dBm is (2*4)-113 = -105 which I found strange but reporting the facts.
In my home office, my signal strength varies between 2-6 ASU or -109 to -101 dBw. If I go outside this will boost to about 8/9 ASU or -97 to -95 dBW.
Moving upstairs to the side of the house nearest our closest radio transmitter (Theydon Bois) the ASU went up to 20 with -73 dBm. Logic would dictate that height in the house is better than being outside and behind the house.
As a further test, if I put my one hand in the normal holding position (bottom of handset), the ASU dropped to about 17 (-79 dBm) and if I enclosed the aerial with both hands this dropped to 14 ASU (-85dBm). When I then turned my body to use it to shield the phone from the signal the ASU dropped to 8 (-97dBm).
So, whilst not scientific, if you are seeing a low signal, holding the phone awkwardly at the top buys you another 3ASU which could mean the difference of one or two bar of signal as below.
I found that at 0-2 ASU I had one bar of signal. 3-5 was 2 bars, 6-10 was 3 bars and 11 and over was 4 bars (maximum) signal. I suppose depending on phone make and model YMMV.
Not sure if anyone found that useful or even interesting but thought I would note it down.
NB