Building FM Mods from scratch requires technical know-how, proper tools and combined concepts of basic requirements for an environmental controlling system like a Fire Detection System. So you are going to need a soldering iron, multimeter or an oscilloscope and some components related with your mod.
The first step is to make out the aims of your FM Mods. Things like making the signal clearer, transmit a little further or save your power are predominant in SDR radios. Like example, if the power from an FM transmitter increased to 100 watts instead of a smaller amount which usually set in standard method like that any increase by around (50% ) or so be possible can occur on broadcast range.
Take apart the FM transmitter, but of course unplug it from its power source to avoid any possible electrical danger. Refer to the schematic diagram of your circuit and find out where the modulation section is (contain capacitors, resistors and others) including modulator IC.
The depth of modulation can be increased by varying the deviation ratio. An initial error of +75 kHz, for example can improve the audio quality and signal strength by approximately 25% over a wider deviation ( ±100kHz ). Change out the existing capacitors and resistors for new ones with different values to make them drift more or less than you would like This can be made for exampe by using a 20 uF capacitor and a150 ohm resistor as shown.
Additionally, it is very important to ensure that this installation needs verification. Further reconnect the power supply and sweep it up using oscilloscope, to verify that output signal frequency vs deviation are within required limits. Refine these settings as needed to differentiate better performance.
This indicates that industry application areas can reveal interesting patterns. Radio broadcasters such as Clear Channel Communications often upgrade their broadcasting equipment replacing stock FM Mods by custom made ones to improve performance according to regulatory compliance. This has included enhancing modulation circuitry and improving power usage, leading to much better transmission quality coupled with lower operating costs.
Custom FM Mods can range in the price. Simple upgrades can range in price from $100 to $500, while complex improvements for commercial broadcasters may cost over $$10,000. The prices here show the extent of the changes and give an impression of using materials.
Pre-emphasis Circuit- A critical design parameter in FM Mods So for example, North American systems by default use a 75 µs pre-emphasis to cut down on high-frequency noise and if you make this change it results in up to 30% less treble which can improve the clarity of sound drastically.
Innovation distinguishes between a leader and a follower – Steve Jobs This logic can be applied to FM Mods, as the ability for creative changes within legal limits will dramatically increase your range of communication.
There are multiple resources available for creating custom FM Mods both at the enthusiast and professional level. Step-by-step tutorials, component kits and forums to the community act as both support resources and motivators. Professional companies such as Rohde & Schwarz provide that, in addition to the necessary elements and instructions needed for total responsible use of FM Mods focusing on building them from scratch.
EDIT: If you want to get more in-depth on custom FM Mods, check out the full resources and step-by-step guides at FM Mods. Source : Researchgate; View Download This list provides a comprehensive link to all the resources that provide deep technical and practical insights into FM Mods addressing underlying methodology accompanied by relevant modification tips for vastly successful performance improvements with 100% retrospectives.