Originally Posted by YoDude

Is it persistent?

Originally Posted by YoDude

I
Must the transmitter be powered up?

Originally Posted by Kurare

One thing to remember with the numbers is that the chip may have some kind of built-in Tx power management by monitoring the actual power pushed to the air vs. power reflected back from the antenna. As the antenna itself seems to be a just a metal sliver with carefully formed shape suited for antenna use and the contact is a standard metal-gold-spring-loaded touch-gold-nickel-copper contact, it is subject to variance in quality from device to device and also WILL vary as the device ages and gets dropped, dusted, humid, squeezed, dipped in beer and so on. The Tx power can quite likely be controlled to some degree by the chip itself, though the problem here is not frying the gain stage - even the maximum output is but a candle compared to the supernova-like relative luminosity of the "real" transmitter stations - but power usage that should always be minimized.

One nasty thing I noticed about the transmitter is that there's quite little fitering from the main power net of the phone to the transmitter. I noticed this when I was trying it with the not-that-good-but-adequate minihifi set I use as computer speakers and not that low sound level as I wanted to hear if the static changed as I played with the settings - the bundled charger distorted the transmitted signal to a horrible shriek that made my cat go from sleepy rest to VERY puffy in about 3,8 µs and resulted in eight bleeding deep puncture wounds on my shoulder, lots of swearing and bodily pain due to the shock from the shriek and the cat wanting to suddenly delocalize itself, which in turn resulted my computer chair toppling over and me lying on the floor, bleeding and wondering what the hell had just happened - and the shrieking just wouldn't stop until got up from the floor and pulled the charger cable - it was closer than the power button for the speaker set.

Perhaps this is why the SW is not sure whether to allow the FM transmitter to work while a power-carrying cable is plugged in?

Originally Posted by fnordianslip

I've ran mine for a couple of hours at 118 and noticed no issues, but am generally using 112dBuV. IIRC an increase of 6dB will double the voltage.

Originally Posted by j.s

Bug https://bugs.maemo.org/show_bug.cgi?id=7425 entered. I am in region 2. /sys/class/i2c-adapter/i2c-2/2-0063/region_bottom_frequency is 87500

If you have a region_bottom_frequency less than 88100 and 88.1MHz is the lowest frequency available to you in the FM transmitter GUI and you want to set a freq below 88.1, please vote for bug 7425.

The reason for 88.1MHz lower limit of the FM Transmitter is to use the common band with FCC countries. Frequencies under 88.1MHz are removed since the allowed output power under 88MHz is lower than on 88.1-107.9MHz band in FCC countries.

This will not be changed.

250 µV/m at a distance of 3 meters from the antenna. This is equivalent to 0.01 microwatts.

Originally Posted by fnordianslip

Voltage expressions in dB use the "20 log rule" whereas power expressions in dB use the "10 log rule", hence the figure of +6dB for a doubled voltage level, and +3dB for a doubled power level.

Edit. Actually, you said voltage and current both increase linearly, and they actually do, as according to Ohms law R=V/I, so V and I rise linearly, but the power goes up exponentially, as P=VI.

Originally Posted by Flandry

Is the value in the /proc/ a voltage amplification? Funny to call it "power_level" if so.