On Raspberry Pi WiFi monitor mode sniffing - not getting data packets
<p>I am doing <strong>wireshark/packet</strong> sniffing stuff on the rpi. I am using an <strong>Alfa AWUS036H wifi adapter</strong> for capturing. On the rpi, over a period of one minute, with my phone streaming youtube, I managed to capture about 200 packets, many of which were just small 801.11 control frames (beacon, etc.) When the same card, connected to my laptop and I run wireshark, I captured almost 10,000 packets in the same timeframe (still streaming youtube). Does anybody have any idea why? Is the rpi's processor simply not fast enough to keep up? Somehow I doubt this.<br>
<strong>My setup is like this:</strong>    </p>

<blockquote>
  <p>• Raspberry Pi Model B+.<br>
  •   One Alfa AWUS036H wifi card.<br>
  • Manually I set up a monitor interface for this card by doing:<br>
  • sudo airmon-ng start wlan0<br>
  •   Then I use dumpcap to stream
  capture data from mon0 out to wireshark on my laptop for viewing. This
  results in about 200 packets/minute.</p>
</blockquote>

<p>Channel of My access point and wifi capturing adapter was same. Both set to channel 2.
I wanted to test and see if there really were just about 200 packets/minute in the air, so I just unplugged the usb hub from the pi and connected it to my laptop. Same deal,
sudo airmon-ng start wlan0
Then capture on mon0 interface in wireshark, I see many more data packets from youtube, and many more control frames, totaling about 5-10,000/minute at peak streaming speed.
Does anybody have any explanation for this? I tried to control for all the parameters I could in switching from pi to laptop, but I cannot figure out why this is happening. 
One more point: sometimes data packets are captured first time I start the device. After that even if I gracefully change state of wifi adapter and start capturing, it do not capture any data packet.</p>