vk2eta
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Hi, my name is John and I am the developer of the AndPskmail application.
If I can share my experience with the Bluetooth interface.
But first let me congratulate the developer(s) of DroidPSK for a great application at an affordable price imho.
Regarding the Bluetooth dynamic range/background noise I discovered that in my case it was related to the device’s dsp processing of the microphone input with agc and noise suppression active in most bluetooth car kits and most likely most headsets too.
I experimented with various levels of input drive and found that a high level was better than a low level as it tends to reduce the effect of the agc and noise reduction.
Also I noted that in practice over the air that did not affect the performance noticeably.
Otherwise I tested the latest version of DroidPSK on Motorola XOOM 3g running 3.2 and on an HTC Desire running 2.3 and both worked well. My only request would be for an adjustable waterfall sensitivity adjustment.
I used the two BT interfaces as described in the http://www.pskmail.com site under the Android section. The car kit handsfree interface schematic and description is in the andpskmail manual and the earpiece headset version is a separate file. Please feel free to reuse, modify and re-publish.
Please keep the great work,
73, John (vk2eta)
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vk2eta
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Hi,
I realised that the issue mentioned above was with the TX side not the RX side.
Looking at the pictures it looks like dynamic compression on the speaker output of the module, which I would expect is to allow constant volume to the user when used as a Bluetooth device.
Regarding the cracking noise, since it seems to vary with the Android device, I would look at the output buffer size. I have increased the size of the output buffers to 10 times the minimum calculated by Android in my application.
Hope this helps,
73,
John (vk2eta)
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Wolphi
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Hi John:
Thank for sharing your information here. Also congratulations on your AndPSKMail app !! I can confirm everything your wrote. I played with it for a while and didn’t didn’t see any performance problems. I looked at the signal on my Oscilloscope and I can the that couple samples are missing sometimes. But as long as the receiver on the other side recognizes the phase shift everything should be ok.
I tried different buffer sizes but increasing the buffer size didn’t improve the cracking noise level.
I used an older hands free module and I also ordered a nice module from http://www.kcwirefree.com. Those modules are not cheap but worth looking into. The module supports regular BT audio and it will support RS232, USB and some I/O pins in the future.
I didn’t see any difference in the quality between the 2 BT devices. I only saw a quality difference when using different phones.
By the way I looked at your AndPSKMail the other day and it will crash on my Galaxy Nexus One as soon as I enable BT in the settings. If you like I can generate an error report in Eclipse and send it to you.
As for the waterfall level. I will put a waterfall adjustment into the settings for the next update.
vy 73
Wolfgang (W8DA)
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vk2eta
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Hello Wolfgang,
Thank you for your comments and the information regarding the BT module. Very interesting. A non-DSP processed signal would be a good thing on top of the possibility of CAT control and more. I need to look into this too.
I have not checked the output of the BT modules with an oscilloscope in my case and have relied only on the IMD information on the receiving Fldig, but I will do so (and might find some surprises too..hihi).
Yes I am very interested in your offer for the log of andPskmail. I am after all the feedback I can get. I will contact you off-list to give you my email address.
All the best,
73, John
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Evan_A
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Hello Wolfgang, I have bought RTTY, PSK and CW Decoder… I have a Yaesu VX-8 with Bluetooth… I can connect VX-8 to an earphone a Motorola H700 in my case… VX-8 sends sound and gets mic audio flawlessly… also when I press the button of this generic earphone that acts as a PTT… so all is there… I was wondering how we can pair it with Android directly… That would be amazing functionality…!
As it is my Motorola Defy plus cant see VX-8… what can we do? Any android hack?
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Wolphi
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I am not 100 % sure but my explanation why it doesn’t work is the following:
The Android device acts as a Bluetooth host and the earphone acts as a client. The same is when you use your VX8. The VX8 is the host and the earpiece is the client. If you want the Android device communicate with the VX8 then 2 hosts have to talk to each other. I know there are different Bluetooth modes but I am not sure if it is possible Android would support this. But like I said I am not 100% sure on this.
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Evan_A
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You have to put android to emulate a headset (client)… It might be tough… but it will do magic… Also there is a huge interest on internet on a simple headset emulator… Thank you for your amezing work…
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Wolphi
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Thank you for the links. I just looked at them and you seem to be right. Android needs to emulate a Bluetooth headset. This also means we need to program a complete Bluetooth stack. Well I have to admit this would exceed my skills by far 
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Evan_A
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Thanks for your efforts… there might be one that can do this on the web…
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Evan_A
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We should list an intent here… http://www.openintents.org/en/
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wb6yte
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Hi. I have a Samsung Galaxy Tab 10.1 tablet and am very interested in trying DroidPSK with it. Unfortunately this tablet does not have an audio input port that could be used for an external mic or a radio.
I have done a little Android software development. I have also explored BT operation between two BT phones and found that it can be done.
I did a little research into Bluetooth devices that can be used as a general purpose audio interface to the tablet but haven’t found any devices that are designed for that purpose. Can you recommend any devices?
Thanks,
Ed
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wb6yte
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I just read through some of the more recent posts about BT support. I will look for a hands free speakerphone adapter like the one I have in the car and see if I can open it and hijack the speaker and mic connections.
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