Pulse Width Modulation
Constant pressure and smart frequency control for optimal coverage
As a farmer or contractor, you know how important a constant pressure is while spraying. A constant pressure ensures a consistent droplet size, which is key for optimal spray coverage. Changing application rates can be quite challenging for a conventional sprayer as application rate is regulated by changing pressure.
That’s where Pulse Width Frequency Modulation (PWFM) comes in – the next step in precise application rate control. With PWFM, the spray valves not only open and close very rapidly, but both the opening time (pulse width) and the switching frequency are managed intelligently. This allows you to adapt the spray output to field conditions and speed, while maintaining droplet size and coverage.
With WEED-IT’s PWFM-based technology, you benefit from:
- Nozzle by nozzle section control / individual nozzle section control.– sections as small as 25 centimetres (10 inches)
- Speed and curve compensation – instant correct application rate, even when accelerating, decelerating or turning
- Every plant the right dose – each plant and weed gets exactly what it needs, no more and no less
- Prescription map – constant droplet size while the flow is adjusted to each plant or zone via PWFM.
Praxis-proven since 1999
Many sprayer and spot-spray system manufacturers only started working with advanced pulse systems in the last decade. At WEED-IT, we have been relying on pulse-based spray control since 2004 already.
Where traditional PWM focuses mainly on duty cycle at a fixed frequency, WEED-IT’s approach has evolved into Pulse Width Frequency Modulation.
The droplet size is kept stable by maintaining a constant pressure.
- Each individual nozzle is controlled so that the right amount reaches the right place at the right time.
With our PWFM technology on your sprayer, you can rely on each individual plant getting the targeted rate and coverage. WEED-IT leaves no weed untouched!
Ideal for irregularly shaped fields
Your fields are probably not straight and perfectly rectangular. Spraying irregularly shaped fields can be tough without the right equipment and tools. No matter how irregular some of your fields are, WEED-IT’s PWFM technology offers the right solution.
- Overapplication on the inside of corners and curves is prevented.
- Underapplication on the outside of curves is minimised.
- Application rates remain correct across the entire boom, whether you are running a constant rate or using a variable-rate application map.
Whatever your tramline pattern, the WEED-IT spraying system uses PWFM to maintain the correct application rate and droplet size, even as speed, direction and overlap change.
Why frequency matters in PWFM
In any pulse-based system, the spray valves open and close several times per second. The frequency indicates how many times per second this happens. With classic PWM, this frequency is often fixed. With PWFM, however, both the duty cycle and frequency are managed to optimise spray performance.
In practice, it is not about having the highest possible frequency, but about:
- Matching the frequency with the duty cycle to prevent skips and stripes.
This is exactly what WEED-IT’s PWFM control does: the system chooses the most efficient frequency for the situation, instead
of simply pulsing as fast as possible.
Intelligent variable frequencies for longer life and better results
- Minimises skips and striped patterns, ensuring even coverage across the boom.
- Maximises spraying efficacy, so every drop ends up where it is needed.
- Reduces electrical and mechanical stress on valves and electronics, extending the lifespan of the WEED-IT spray valves.
The result: robust, long-lasting hardware combined with extremely precise application – even under demanding field conditions and at varying speeds.
With PWM vs. without PWM: the difference in your potato field.
|
With PWM | Without PWM | ||
|---|---|---|---|---|
| 1. Application rate in turns |
|
• Too much on the inside of the turn • Too little on the outside of the turn • Outside turn = earlier risk of Phytophthora |
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| 2. Crop coverage | • Constant droplet size • Reliable, even coverage |
• Varying droplet size • Uneven coverage with changing speed |
||
| 3. Product effectiveness | • Precise deposition • Optimal performance → higher reliability |
• Variable output → reduced effectiveness • Higher risk of reduced control (rain, rapid growth) |
||
| 4. Working speed |
|
• Higher pressure → smaller droplets → more drift (l/ha remains constant) • Braking & turning cause issues |
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| 5. Waste vs. efficiency | • Exactly what is needed, where it’s needed • More efficient use of products & time |
• Over-application = waste • Under-application = infection risk & extra costs |
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Get in touch
Do you have any questions about our products? Need advice on effective weed control? Or perhaps you’d like to share your experiences? Whatever inquiry you have, we’re here to assist you. Just drop us a line, and we’ll get back to you as soon as possible.