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Audio recording


#1

Several activators record their activation’s audio (TX and RX) with good results, as can be heard on YouTube videos.

Would they be kind enough to share their experience and recommendations about how to proceed, and especially how to avoid the wind noise with the TX/RX audio, and how to balance the CW side-tone (TX) ?

The setup is quite straightforward at home, but more challenging outdoors…

Thank you in anticipation.


Accessible Summits
#2

Old MP3 player with line in, Record mode. Run the headphone output through a line tap and adjust the TX monitor output. (KX3).

Jonathan


#3

Here my expericences regarding SSB:
Old Nokia 5800 mobile phone with the audio recorder app just put somewhere near the rig. Works fine with FT-817 which I use with the internal speaker. Not tested during strong wind - I only occasional take audio recordings.
Same technique does not work with the KX3: Due to its extremly poor audio output I am obliged to use headphones here. So no speaker output for the phone microphone.

73 de Michael, DB7MM


#4

I would recommend the olympus digital voice recorder series. I have used my VN-1000PC to record my activations simply to check my logging. I bought one after finding one very wet lying in the grass in Coquetdale. I dried it out in a warm cupboard at home and when I powered it up, I found out that it belonged to the military and had been used to record a briefing about 5 weeks previously. It had lain in the wet for probably all of those 5 weeks. My thoughts were simply that if the military will use these in the field and given that it had survived 5 week exposure, I was sure one would be fine for activating, A few days later, I spotted a military Land Rover and gave it to them. With a quick listen they immediately identified the potential owning regiment.
73 Jim


#5

Similar here.
I rarely take video during an activation as I normally wear earphones especially if it’s windy.
When I do record audio, I use a little portable speaker plugged into the rig.
You can see it here at 45secs.

The camera I use ([Mobius][1]) seems to pick the audio up pretty well.
I’ll only record when there is no one else around as I feel it’s wrong to make any noise (other than key clicks) on a summit when others are present.

I have considered recording all my audio with a splitter and MP3 recorder. That way I can replay and log at home in the warm and dry. I also get the pleasure of the activation twice :slight_smile:
[1]: https://www.mobius-actioncam.com/
Pete


#6

I don’t often record my activations but I have done in the past. I use a Philips digital recorder. I built a splitter with potentiometer so I can control the level going into the recorder. I find the Audio hits the AGC very easily.

The recorder has a microphone bias voltage coming out of the mic in socket, so I used a capacitor for DC blocking.

73, Colin


#7

If you aready have an Android based phone with you, I have found the Hi-Q MP-3 recorder app to be very good - simply start it and stand it near the rig. Not as good as wiring in a proper recorder but a simple solution and no additional cables of equipmenet to carry and possibly lose.

If you want to do a video, I always take along my small Nikon Coolpix P7100 DSLR camera for still pictures and it can also record a respecatble video at 720p with audio.

I usually run SSB, so I need both the receved audio and the sent audio recorded - so from rig and from air recording whether audio only or video.

Ed.


#8

HamLog (Pignology) on Android has a built-in recording tool (and other stuff, some of which is useful). Especially in the British winter (and often in spring/summer/autumn) my phone lives in a watertight holder, so an electrical connection is not an option. Of course if I had an interface to the phone I’d want to make it two-way and do digimodes!


#9

Thank you for all the replies.

I’ll experiment during my next activations.


#10

How does it affect battery life?
What bitrate do you use and how many kb or mb per say 10 minutes do you get?

I have been thinking of recording my activations to double check my logging.


#11

Typical sampling rate 48 khz -> 48 K samples per second. Higher rates are achievable,

X 60 Seconds in a minute. You asked for 10.

-> (48 * 10 * 60)K = 28800 Kbits for a typical MP3 file. Equates to 3600 KB (3.6MB)

Probably terribly… I would rather save it for an emergency but that depends on what you activate in certain weather condx :wink:


#12

I have had no issue with battery life using the recorder in the phone. WiFi, GPS and mobile data (3G) features appear to be the things that drain the mobile phone battery the most.

I have the recording bit rate in the HI-Q software set to 64k at the moment which uses 0.5MB/minute of recording but taking it down to 32k (0.24MB/minute of recording and the lowest setting in the software) isn’t going to be an issue - we’re not looking for concert hall quaity audio are we? If you are afraid of filling the available disk space in the phone, you can set a minimum amount to leave free at which point the recording will stop.

Ed.


#13

As an alternative to Pigremote, here’s an Android Phone to rig (Yaesu FT8x7 standard, make up your own lead to other rigs) - also Android digital mode software from the same source:
http://www.wolphi.com/interface/

Ed.


#14

Hello!

With my KX3 I am using an Olympus Digital Voice Recorder VN-711PC, which records mp3.
I made a splitter-cable for the phones-plug including a simple built-in 10:1 voltage divider (100kOhm in seriell, 10kOhm in parallel). The small resistors are inside the plugs (one in the phone plug and one in the mic-plug to the recorder).
That workes quite well!

73 de Chris, OE3CHC


#15

Phones come with disks now :confused:


#16

Apparently so! Here’s my phone’s disk.


#17

Well MP3 is an asymmetric process, decode is designed to require less resource than encode. However, a modern smartphone will have 12 or more processor cores on board plus GPS, Bluetooth, Wifi, graphics etc and also some audio processing and RF stages. 10mins of MP3 recording is going to appear as nothing substantial… the audio hardware is already designed for uber-low power so you can use the phone as an iPod without sacrificing the ability to make calls or use the data connectivity. If a 10min recording session exceeds the power need to make a 30sec phone call I’d be surprised. Most smartphones have talk-times of 4-8 hours.


#18

Thanks Ed. Useful info. My phone (Galaxy S5) has a MicroSD card though probably needs a spring clean to clear out dead photos and videos as it ran out and started using the internal memory for the camera a while back. (Mind I was storing several 100 DSLR RAW files from a USA road tip on there then)
As I use headphones that complicates it for me. I could use a Y splitter on incoming audio, I guess that would preclude my outgoing audio.

thanks


#19

Picky Jonathan, picky! SD Card, Internal Memory ROM - whatever.

Lets just say “storage space”.

I used disk space to avoid confusion with RAM memory.

Ed.


#20

Seriously, we need to be picky. Don’t let a candy eyed OS make it OK either, its WRONG !

Yeah fine !