# Voice and Voltage mapping to frequency

#### berrymaleek

Joined Mar 22, 2018
8
My project is about creating a transmitter using the low frequency range (30kHz -300kHz), I am in need of of the right circuits to put together that would map both the voice and digits to frequency, that is, for every sample inputted into the system through a mic condenser for example, frequency is being generated and for the digits, for every key pressed, the voltage levels are converted to frequency and can be transmitted at low frequency range. I hope the little explanation given gives an idea of what I am trying to talk about and any help what so ever will be really appreciated.

#### ericgibbs

Joined Jan 29, 2010
14,659
hi berry,
Welcome to AAC.
When you say 30Hz > 300kHz, I assume you mean RF transmission.?
Do you have a diagram you could post.
E

#### berrymaleek

Joined Mar 22, 2018
8
yes I'm referring to RF, the frequency range of 30kHz and 300Khz. Basically trying to build wireless intercom but I'm just working on mapping voice samples and the voltages from the keypad to frequency.

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#### berrymaleek

Joined Mar 22, 2018
8
hi berry,
Welcome to AAC.
When you say 30Hz > 300kHz, I assume you mean RF transmission.?
Do you have a diagram you could post.
E

yes I'm referring to RF, the frequency range of 30kHz and 300Khz. Basically trying to build wireless intercom but I'm just working on mapping voice samples and the voltages from the keypad to frequency.

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#### berrymaleek

Joined Mar 22, 2018
8
hi berry,
Welcome to AAC.
When you say 30Hz > 300kHz, I assume you mean RF transmission.?
Do you have a diagram you could post.
E

hello Eric,
Do you think you can help me out please??

#### ericgibbs

Joined Jan 29, 2010
14,659
hi berry,
I was hoping a member with experience in this type of project would come forward to help you.
It is a fairly complex project that you are proposing.
Give the Thread a couple of days, someone may help.
Eric

#### BR-549

Joined Sep 22, 2013
4,938
I don't understand your post. Can you compare what you what to do.....to something similar or that has already been done?

#### berrymaleek

Joined Mar 22, 2018
8
I don't understand your post. Can you compare what you what to do.....to something similar or that has already been done?

ok basically, it's like trying a to build a wireless intercom but I'm concerned with part of mapping the voice signal to frequency and voltage from the keypad also mapped to frequency in the 30kHz-300kHz range.

Plainly I would describe the whole like this: I speak into a condenser mic (input to the system), the voice gets sampled at different levels, then frequency is been generated as the out for transmission.

Then the keypad, I dial digits to be transmitted on a keypad then the voltages from each digit is mapped to a frequency for transmission.
These frequencies should be readable on a frequency meter. I hope this is more explanatory???

#### LesJones

Joined Jan 8, 2017
3,646
So are you saying that you want to convert the analogue voice signals to a digitaly encoded signal before you modulate the 30Khz to 300Khz carrier siganl with the digital data stream ? If so do you want to use one of the standards such as MP3 or AAC or are you using your own coding system ? Are the signals from the keypad being first converted to DTMF before transmission ?

Les.

#### berrymaleek

Joined Mar 22, 2018
8
So are you saying that you want to convert the analogue voice signals to a digitaly encoded signal before you modulate the 30Khz to 300Khz carrier siganl with the digital data stream ? If so do you want to use one of the standards such as MP3 or AAC or are you using your own coding system ? Are the signals from the keypad being first converted to DTMF before transmission ?

Les.

On point! Not sure which is best and simpler between the AAC or trying to code on my own with a different system so as not to get stuck and preferably move from known to unknown. Yes the keypad should be converted to DTMF before transmission. If this can be achieved I'm to use a digital frequency meter as means to confirm that frequency is really transmitted and varies in the range of 30kHz-300kHz.

#### Papabravo

Joined Feb 24, 2006
17,551
The frequency range you have chosen has a number of inherent difficulties:
1. The required antenna size makes an efficient transmitter/receiver difficult to achieve.
2. The required bandwidth is a significant fraction of the carrier frequency.
3. The component sizes required for passive filters are large and unwieldy.
I recommend that you start with a higher frequency. One that lies withing a recognized band for unlicensed operation.

#### berrymaleek

Joined Mar 22, 2018
8
The frequency range you have chosen has a number of inherent difficulties:
1. The required antenna size makes an efficient transmitter/receiver difficult to achieve.
2. The required bandwidth is a significant fraction of the carrier frequency.
3. The component sizes required for passive filters are large and unwieldy.
I recommend that you start with a higher frequency. One that lies withing a recognized band for unlicensed operation.

It's a project that is based on achieving communication at the low frequency range of 30kHz-300kHz, the difficulties you listed have been talked about and the project is required to beat that. It's meant to serve as a wireless telecom take for example a university campus so no registered carrier is needed just a base station that serves as an exchange between parties

#### ericgibbs

Joined Jan 29, 2010
14,659

Joined Mar 10, 2018
4,057
Yes, you could consider PSOC. The mapping of key to frequency quite simple,
use Wavedac component and Debounce component for key, when key is pressed
you use a lookup table for freq for that key and write that into Wavedac control
register. This will allow you to gen sine or whatever waveform you wish. You would
use external clock on Wavedac option, and using a timer to drive the wavedac clock change the sample rate of Wavedac hence its output freq.

For translating voice to RF you need mixer, PSOC also has one that could possibly
work.

Look at PSOC 101 video series to get started, I would recommend this
board to use. Google "psoc 101 videos" to get URLs to watch.

http://www.cypress.com/documentatio...oc-5lp-prototyping-kit-onboard-programmer-and

This is all onchip and lots of other stuff, analog and digital.

Regards, Dana.

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#### Papabravo

Joined Feb 24, 2006
17,551
It's a project that is based on achieving communication at the low frequency range of 30kHz-300kHz, the difficulties you listed have been talked about and the project is required to beat that. It's meant to serve as a wireless telecom take for example a university campus so no registered carrier is needed just a base station that serves as an exchange between parties
You have conflated "RF Carrier Frequency" with "Common Carrier". The former is the method of transmitting a signal and the second is like a telephone company. The US spent a great deal of time and money on low frequency RF communications and ultimately abandoned their plans. Your project is likely to meet a similar fate. To cover a campus wide area you will need licensed transmitters, even for experimentation.

#### BobaMosfet

Joined Jul 1, 2009
1,917
This is a Digital Signal Processing project; sounds like homework or thesis material. Might just be a cool-in-school project for you and your mates, but honestly, go to your stax or campus library and find a couple of books on digital signal processing, PWM, Shift Key, and ATM. In fact, if you look about DS1/T1 signalling, you may learn exactly what you're looking for in how the voice is chopped and encoded and signaled.

#### berrymaleek

Joined Mar 22, 2018
8
Yes, you could consider PSOC. The mapping of key to frequency quite simple,
use Wavedac component and Debounce component for key, when key is pressed
you use a lookup table for freq for that key and write that into Wavedac control
register. This will allow you to gen sine or whatever waveform you wish. You would
use external clock on Wavedac option, and using a timer to drive the wavedac clock change the sample rate of Wavedac hence its output freq.

For translating voice to RF you need mixer, PSOC also has one that could possibly
work.

Look at PSOC 101 video series to get started, I would recommend this
board to use. Google "psoc 101 videos" to get URLs to watch.

http://www.cypress.com/documentatio...oc-5lp-prototyping-kit-onboard-programmer-and

This is all onchip and lots of other stuff, analog and digital.

Regards, Dana.

Really appreciate this, I will try the psoc out but I want to confirm if it can be tweaked to transmit in freq range of 30kHz-300kHz, are the waveac8 and the mixer_1 embedded in the psoc and can I be able to use a frequency meter to monitor the frequencies generated???

Joined Mar 10, 2018
4,057
You can use PSOC as well to create a frequency counter and display on
LCD, or uart to PC for display.

The mixer component datasheet (just for that component inside PSOC) -