FPV is in a phase. The next few years are going to decide if FPV will stick to Analog Video transmission or Digital convert Transmission. DJI changed the FPV scene with the first compact digital FPV system. Digital HD FPV systems are limited to DJI for now, with companies like Fatshark and Orqa FPV working on Digital systems as well. Analog systems on the other hand have a wide range of options from dozens of manufacturers.
Analog video transmission has been the standard for the past decade and has performed exceptionally well. A new wave of Digital video transmission technology is threatening the dominance of Analog systems. These two technologies vary a lot: Analog systems transmit the electrical signals as is, which is prone to interference and external noise, while Digital systems convert the electrical signals into digital data and get transmitted to FPV Goggles.
What is Analog FPV
The term analog FPV refers to Analog video transmission technology and systems. Analog systems work by varying the amplitude or frequency of the wave. FPV cameras make use of Frequency modulation (Modulation is the process superimposing the modulated wave onto the carrier wave), the variations of the frequency are characterized by the features captured by the Camera. An FPV camera captures the video, known as a modulated wave, and sends this captured signal in the form of a sine wave to the FPV Video transmitter.
The FPV camera signal is passed through to the VTx. The VTx have a carrier frequency (carrier frequency are frequencies that help the weak FPV camera signal to travel over long distances), the most commonly used carrier frequency is 5.8GHz. The carrier frequency is the frequency in which the wave is transmitted.
Analog transmission signals constantly vary. This is a technique used in electronic communication and works by alternating the strength of a transmitted signal about the information that is being sent.
What is Digital FPV?
Digital devices are everywhere, Laptops, smartphones, calculators... the list is endless. Digital processing makes use of 1’s and 0’s, 1 indicating a higher state and 0 denoting a lower state. Digital data transmission is also known as data transmission, equating to the literal sense that data is sent from point A to point B.
For one thing, the digital signal is much simpler. Rather than being a continuously variable waveform, it is a series of discrete pulses, representing one and zero. In electrical networks, one is represented as high voltage, and zero is represented as null, or low voltage.
Digital systems take the electrical data from an FPV camera and convert them into digital signals with the help of ADC (short for Analog to Digital converter). The transmitting module has an Encoder that encodes the data of the FPV camera into O’s and 1’s and the receiving module has a Decoder that decodes the digital data into Analog signal before bring displayed onto the goggles.
Analog vs Digital FPV Systems
The main difference being that the Analog systems transmit raw analog data while a Digital system transmits digital data.
Low - Avarage
Signal to Noise Ratio
Medium - High
Video Transmitter Cost
Video Receiver Cost
Low - Medium
Susceptibility to External Noise
Medium - High
Nano - Medium
Medium - High
Low - Medium
Low - Medium
Cost plays a major role in picking between Analog and Digital systems. Analog Video Transmitter and Receiver combo can be had for as little as $100, whereas the Digital system can cost upwards of $600.
Signal to Noise ratio
This factor refers to the signal strength received. In simpler words, a Video transmitter placed close to a receiver, the surroundings cannot contaminate the transmitted signal with external noise, can ideally have a signal-noise ratio of 1. As the transmitter moves farther away from the Video receiver, the environment plays a significant role in diminishing the quality of the received signal.
Video Transmitter cost
A digital video transmitter from DJI, as of this writing in mid-July 2020, costs $179 compared to the $50 TBS Unify pro, an Analog Transmitter costs. If you have 10 quads that need video transmitters, the price difference between the two systems is $1290.
Video Receiver cost
Even though this might be an onetime investment, there are lots of cheap FPV goggles to choose from, ranging from $100 up to $600 with Fatshark HDO v2 and Rapidfire module. Digital goggles and receivers come in a package and can cost between $450-500 depending on when you buy.
Susceptibility to external noise
Analog systems are more vulnerable to external noise, most noise is Analog in nature, and Digital systems are less likely to be disturbed by external noise.
The next deciding factor becomes the form factor. There are plenty of options when it comes to small Analog transmitters as opposed to the bulky size of a Digital Transmitter.
Analog systems are proven to provide ranges over 20km as compared to the 2km a digital transmitter offers.
Latency is the time taken for the video signals from the quad to reach the goggles. Modern DJI FPV video systems greatly reduced the latency to around 35ms while the Analog systems take the win at around 15ms.
evolution of Analog to Digital
The Audio cassette - the tape is a recording format that was first introduced in 1963 to fill a need in the then available audio recording media options. Tape recorders are what we call analog storage devices. Tape recorders involve the use of a magnetizable medium that moves with a constant speed past a recording head.
An electrical signal, which is analogous to the sound that is to be recorded, is fed to the recording head, inducing a pattern of magnetization similar to the signal. A playback head can then pick up the changes in the magnetic field from the tape and convert it into an electrical signal.
The first DVD players were made available in November 1996 in Japan and eventually made its way to the United States in March 1997. DVD’s were the beginning of an era of digital storage and the end of a 3-decade long dominance of Analog storage. DVD stores the electrical data in the form of 0’s and 1’s. DVD’s were rather successful as they could store large amounts of data in a rather compact size.
The late ’90s and early 2000s were turbulent as the 2 wholly different technologies fought for dominance and eventually Tape recorders lost. Apart from finding in thrift stores and our grandfather’s old storages, Tape recorders are nonexistent today.
Analog vs Digital FPV Conclusion
Now time for an answer!!! FPV Analog or Digital, I'd say both. If all you do is casual Freestyle flying and the cost doesn’t bother you, I’d say go Digital. If anything, the latency and the cost is only going to get better. If you do Racing, where the size and weight matters, Analog is the better choice. Analog also suits well for budget-constrained builds. Analog is on its last leg.