To begin your FPV journey you need at least these 4 items:
A video transmitter – To transmit the picture to the ground
A video receiver – To receive the picture on the ground
A camera – To have a picture to transmit
A video display/goggles – To watch the video feed from the airplane
This is the BASIC setup, the absolute necessary stuff to be able to fly FPV. I recommend to start out simple and then expand with the more advanced stuff once you mastered the basics.
The video transmitter
At the moment there are 4 different frequency bands to choose from when it comes to transmitting video, and they are; 900MHz, 1.3GHz, 2.4GHz and 5.8GHz.
Before you choose what frequency you want to use you need to do some research of what frequencies that are allowed in your country, for example; 900MHz is not allowed in Sweden because it’s used by air traffic, and if any license is needed to transmit on any of these frequencies. In most countries you are allowed to transmit up to 10mW of video on the 2.4GHz band without a license. You also need to take into account what frequency your RC transmitter utilizes; if you fly on 2.4GHz, you can’t use that frequency for your video link as well.
Here is a list of the pros and cons of the different frequencies:
900MHz and 1.3GHz
+ Less influenced by obstacles due to lower frequency
+ much less “crowded” frequency
+ Works with 2.4GHz RC transmitters
- can interfere with GPS signal
- hard to find antennas
- not that many transmitters/recievers to choose from
2.4GHz
+ Easy to find a wide variety of antennas
+ Many transmitters/recievers to choose from
+ Doesn’t interfere with GPS as much
- More influenced by obstacles
- More “crowded” frequency
- Don’t work with 2.4GHz RC transmitters
5.8GHz
+ Easy to find a wide variety of antennas
+ Doesn’t interfere with GPS as much
+ Works with 2.4GHz RC transmitters
- Even more influenced by obstacles
- More “crowded” frequency
- not that many transmitters/recievers to choose from
A 1.3GHz 300mW transmitter
Ok, now that you’ve chosen the frequency you need to know how much power to get.
“There is no such thing as to much power” – Or is there?
A transmitter with higher power will:
+ Have longer range
- Be bigger
- Be heavier
- Produce more heat and may require a heat-sink (even more weight)
- Draw more current
- Be less efficient
A common misconception is that doubling the transmitter power will give you double the range. This is not true, doubling the transmitter power will only give you 1.414 times longer range (The square root of 2 or 3dB). The best choise in my oppinion is to use a smaller transmitter and a patch antenna (more about antennas later on) on the receiver to get extra range as you normally won’t fly 360° around yourself.
There is no use in having trice the range on your video link than on your RC link. These are my suggestions if you use a standard RC link:
~300mW 1.3GHz / 900MHz transmitter
or a
~500mW 2.4GHz / 5.8GHz transmitter
Plus a ~9dBi Patch antenna for the receiver
These combos easily gives about 2-4km of crisp video which is more that you need if you fly with a common RC link. They will also be light, use less current and not be prone to overheating. A good balance for your first setup.
The Receiver
This is the easy part. When you buy a transmitter you will almost definitely be able to buy a matching receiver from the same place. As long as the receiver works on the same sub frequencies (ex 910MHz, 915MHz..) as your transmitter your good to go. Sometimes you will have the choice to buy a “dual output” receiver, which means that is has two composite outputs, which is nice if you want to record you flights or have a “passenger” screen/goggles. But you can get a separate composite “splitter” later on if you want to.
The camera
Any camera that has a composite output will work but there are some qualities to look for in a camera when picking one for FPV use. The most important one is fast brightness adjustment, this is because the brightness varies so much and so fast during a normal FPV flight. If you use a camera that’s slow to adjust its brightness you will end up with a useless picture during nearly the entire flight, and you might even crash.
Other qualities to look for is obviously small and lightweight. But now comes the tricky bit… Image quality. Why is this the tricky bit? Because “beauty is in the eye of the beholder”. Different people value different things when it comes to “image quality”.
Some like bright colors, some like a brighter picture, some like higher resolution and so on. This is why I can’t say; “Buy this camera, it’s the best one”. You need to compare different cameras your self to find the one you like the best, and the simplest way to do that is to watch other peoples FPV videos. But before you do that here is a good thing to know:
There are two different types of sensors that is used in cameras; CCD and CMOS. (The sensor is the part that actually captures the light and converts it into a digital image.) These two sensors work in different ways and both have their strengths and weaknesses. Neither is categorically superior to the other. I will try to summarize the pros and cons for the use in FPV of both these types:
CCD:
+ Better in low light situations
+ Low noise
+ More pixels/area
- Suffers from “smear”/“bleed” (Vertical lines when exposed to bright light)
CMOS:
+ Eatch pixel can have brightness/contrast correction
+ Less power consumption (up to a 100 times less!)
- Picture gets distorted with vibration (wobbly image)
Modern CMOS sensors has an advantage over the CCDs and that is that they can adjust the brightness/contrast of every pixel. This means that you can see both the ground and the sky correctly exposed at the same time! This is where the CCD struggles, on a sunny day you either see the ground correctly exposed or the sky but not the both at the same time.The CCD also suffers from “smear”/“bleeding” which means that when pointing the camera at a bright light, lines appear in the picture which can in turn lure the camera to underexpose the picture. Here is a picture of the phenomena. However the CCD has an advantage when it comes to handling vibration. On a CCD the picture simply gets a little blurry with small vibrations, where on the CMOS the picture gets “wobbly”. Here is a video of the phenomena. This can be a problem especially if you want to use a heli for FPV. On an airplane this should not be a problem if you have a properly balanced prop. If you want to read more about CMOS vs CCD this homepage is a good place to start
Most cameras that can be found in FPV shops are relabeled security cameras, f.ex the real name of the KX-171 camera I’ve used is “480 tvl 0.2 lux, 1/3″ SONY® super-HAD® CCD, 12VDC”.
Matching equipment
One thing to consider is to choose a video transmitter and a camera that operates on the same voltage, as this simplifies the powering of the two. If you use a 12V camera and a 12V video transmitter you can simply run both of them directly of a 3s LiPo. If you use a 5V setup you need a voltage regulator which adds extra weight and you will lose some efficiency. I recommend using a separate battery for the FPV equipment, it’s much less trouble than powering them from the main pack as you most certainly will experience severe interference in the video link. (Altho this can be overcome buy adding a couple of filters)
The display/goggles
Now that you’ve chose the video transmitter and camera you need something to display the image you’re transmitting. The cheapest alternative is to get a small TFT display, like 7”, and mount it inside of a box to block out sunlight, a so called “Geek box”. It’s cheap but isn’t very practical (nor good looking). Just be sure the screen has at least 640*480 pixels of resolution. An other alternative is to buy your self a pair of video-goggles.
They are much more practical and in my opinion give a much better experience when FPV flying. When choosing video-goggles I recommend a pair with at least 640*480 pixels resolution. Any lower and the experience will suffer greatly as it will “smudge” out the picture, destroying the details. Another figure to look out for is the FOV (Field Of View) angle number. This number tells you how big you will experience that the picture is. A higher value is better. When this is written the goggles with the best FOV is the Fatshark RCV922 with 46°. Not all manufacturers print this number, but some does gives a size of a “virtual” display experienced at 1 meters distance, usually 58” or something similar. Also in this case the higher value is better. Other than that it’s not much to look out for when choosing goggles. If you get a chance to test the goggles on before you buy them, take it. Try them on and make sure they feel “right”.
You’re done!
You now have what you need to do your first FPV flight. The next segment will cover the more “advanced” stuff that you might want to get further down the road. I will not be as “indepth” about these topics thou, but rather give you a simple taste of what they are. Even if it isn’t needed to fly FPV I strongly recommend getting yourself a recorder to be able to revisit your flights. This will help a great deal when learning to fly from the airplanes perspective. I can also recommend getting a patch antenna from the start, they are a cheap way to increase your range at the cost of 360° reception. But how often do sit in the middle of the field and fly around yourself?
