Increase +30% the freq of the signal

Thread Starter

Mullins

Joined Dec 31, 2021
179
Hi everyone. I want to ask for advice on the best way to increase the frequency of a signal (for example +30%) without altering the rest of the characteristics. Gemini recommends using an op-amp. What do you think about it?
 

MrChips

Joined Oct 2, 2009
30,986
Hi everyone. I want to ask for advice on the best way to increase the frequency of a signal (for example +30%) without altering the rest of the characteristics. Gemini recommends using an op-amp. What do you think about it?
No. An op amp cannot do that. You need to sample the waveform and then selectively remove some samples.
 

BobTPH

Joined Jun 5, 2013
9,177
Hi everyone. I want to ask for advice on the best way to increase the frequency of a signal (for example +30%) without altering the rest of the characteristics. Gemini recommends using an op-amp. What do you think about it?
For an arbitrary waveform? I don’t believe that is possible to do with analog circuitry.

Digitally, you could sample the input waveform and regenerate the output at a higher frequency.
 

Alec_t

Joined Sep 17, 2013
14,382
Why do you want to do this? If we know the reason you are more likely to get helpful replies.
What signal is it? Amplitude? Frequency? Waveform?
How important is it to preserve waveform or amplitude?
How much latency (time delay) is allowable in the conversion?

If the signal is an audio recording then the freeware Audacity app could do pitch shift.
 

Thread Starter

Mullins

Joined Dec 31, 2021
179
I would like to point out that this is all for educational purposes. Please don't bring up safety issues etc... I would like to fit a gearbox that has different ratios from the original one. Since in the past I had problems with another car because The different ratio caused interference with handling and braking. This time I want to simulate a different ratio. To do this I need to process the ABS sensor signal so that it gives a higher frequency. Example: At 100km/h the ABS sensor produces 100Hz. I would like a device that receives a wave at 100Hz and returns it at 130Hz. By doing this I make the system believe that I have mounted a gearbox with different ratios from the original. If I don't get any errors and everything works fine I can Install a gearbox with ratios different from the original.
 

Ian0

Joined Aug 7, 2020
10,067
I would like to point out that this is all for educational purposes. Please don't bring up safety issues etc... I would like to fit a gearbox that has different ratios from the original one. Since in the past I had problems with another car because The different ratio caused interference with handling and braking. This time I want to simulate a different ratio. To do this I need to process the ABS sensor signal so that it gives a higher frequency. Example: At 100km/h the ABS sensor produces 100Hz. I would like a device that receives a wave at 100Hz and returns it at 130Hz. By doing this I make the system believe that I have mounted a gearbox with different ratios from the original. If I don't get any errors and everything works fine I can Install a gearbox with ratios different from the original.
In a perfect world you would use a phase-locked loop and multiply the frequency by 13 and divide by 10, but getting a phase-locked-loop to lock at any frequency between 0 and 160Hz (equating to a speed between 0 and 100MPH) isn't trivial.
 

LowQCab

Joined Nov 6, 2012
4,218
There is Software available for many Cars that will allow You to simply type-in the present Gear-Ratio,
( and sometimes also the Tire-Diameter ), to correct the Speedometer, the ABS System, and Automatic-Transmission Shift-Points.
Then there will be zero guesswork and 100% reliability and safety.

Who is the manufacturer, and what is the year of your Car.
.
.
.
 

Thread Starter

Mullins

Joined Dec 31, 2021
179
@LowQCab
The car is Focus MK2. Ford IDS allow me to change me the tyres size. I ca do it, but the ratio between crankshaft and drive shaft will remain the same. I will get different speed on instrument cluster depending by th tyres size. Instead I need to change the frequency of the signal of abs sensor. I want to see if the control unit reports any anomaly when it receives a signal with a different frequency than it expected.

@Alec_t
The sensor is hall effect 2 wires
 

MisterBill2

Joined Jan 23, 2018
19,045
OK, now I am GUESSING that the signal is a pulse string, and so a square type of output would be acceptable to whatever logic follows.
I did a similar thing some time ago to display RPM correctly on a frequency counter with a one second time base. The signal was a pulse train from the engine spark system.. So I had to multiply the pule rate by 4.5 to get the correct speed display. The scheme I used was that every input pulse would gate nine pulses from a higher frequency source to a divide by two flip-flop, which resulted in four and a half pulses out for every input pulse. The faster signal I used was taken from a tap on the divider string for the counter time base.
So to multiply by 1.3 each pulse in will need to gate 13 pulses to a divide by ten counter, which would be a CD4017, using the carry out output. That will give a 50% duty cycle. You will need a higher frequency signal source, but it will not need to be perfectly constant.
 

LowQCab

Joined Nov 6, 2012
4,218
This Project amounts to a crazy amount expense and effort for a very dubious increase in Vehicle Performance,
and a likely reduction in Fuel-Mileage,
and a definite reduction in reliability,
( unless the TS is really well versed in building Automotive-Grade-Electronics ).

Every effort towards PCM reprogramming / adjustments should be explored first,
before adding questionable add-on-Circuits.

.
.
.
 

BobTPH

Joined Jun 5, 2013
9,177
This Project amounts to a crazy amount expense and effort for a very dubious increase in Vehicle Performance,
and a likely reduction in Fuel-Mileage,
and a definite reduction in reliability,
( unless the TS is really well versed in building Automotive-Grade-Electronics ).

Every effort towards PCM reprogramming / adjustments should be explored first,
before adding questionable add-on-Circuits.

.
.
.
Not to mention a likely malfunction of a safety feature.
 

Thread Starter

Mullins

Joined Dec 31, 2021
179
In analog you can measure the freq. of signal with f to V converter. Make correction of V as you need and generate new f from this voltage using oscillator.
Please @Michal Podmanický give me some example on internet.

Every effort towards PCM reprogramming / adjustments should be explored first,
before adding questionable add-on-Circuits.
Please @LowQCab let me explain better...
The circuit that I'm looking for is only to make a test, less than 10km. It will not be fitted on the car. It will only permit me to know if this car get some issue when receive a different gear ratio. It will save my time and money to prepare a new gearbox with different gear ratio. Let me give one example:
Fiat Grande Punto can accept any gear ratio. All the system will work fine. This car is have made almost 150.000km since I made it in 2015.
Fiat Grande Punto with "cruise control" accept only original gear ratio. If you put a different gearbox the "cruise control" will not work an mil lamp will stay always on.

Gemini tell me that I can do it even with Arduino
Code:
const int analogInPin = A0; // Pin di ingresso analogico
const int pwmOutPin = 9; // Pin di uscita PWM

void setup() {
  Serial.begin(9600);
  pinMode(pwmOutPin, OUTPUT);
}

void loop() {
  // Leggere il valore analogico in ingresso
  int analogValue = analogRead(analogInPin);

  // Calcolare la nuova frequenza desiderata
  float newFrequency = analogValue * 1.3;

  // Impostare la frequenza del PWM
  analogWrite(pwmOutPin, newFrequency);

  // Stampare il valore analogico in ingresso e la nuova frequenza
  Serial.print("Valore analogico in ingresso: ");
  Serial.print(analogValue);
  Serial.print(" Hz");
  Serial.print(" Nuova frequenza: ");
  Serial.print(newFrequency);
  Serial.println(" Hz");

  delay(10); // Tempo di attesa tra le letture
}
my doubt is about the delay I dont know if 10ms is fast enought.
 

Alec_t

Joined Sep 17, 2013
14,382
By doing this I make the system believe that I have mounted a gearbox with different ratios from the original.
I'm no auto-expert but I would assume any self-respecting ECU would throw an error message if the ratio of the ABS sensor frequency to the crankshaft sensor frequency differs from what it has been programmed to expect, since the difference is likely to affect engine performance, required fuel mappings, emission control and ABS function.
Does your insurer approve of the gearbox swap?
 
Top