"NTFS signature is missing." How to mount this HDD? (or is it password protected?)

I'm trying to mount a hard disk (SATA-3), but I rest stuck at the error:

NTFS signature is missing

Is it possible that a hard disk is protected by a password or has another kind of protection? How should I check if this is the case? And if it is yes or not protected is there a way to mount the disk anyway and retreive the files on it?

Below: the things that I've already tried and as much as error information.

I'm working on Linux (Mint 18.1).

First some background information:

I have an older commercial hard disk recorder (Pioneer DVR-LX61) and its HDD has no space anymore, it's full; I want to move the recorded video files to my computer. I linked the HDD-recorder to my network, but I couldn't mount the disk as it asked me for a password for user root. I took the hard disk out the recorder and connected it directly to my motherboard (with SATA-3 connection). I'm now trying to mount it, but I get into the mentionned errors.

This is what I've done so far:

mycomp@mycomp ~ $ sudo fdisk -l
Disk /dev/sdc: 232.9 GiB, 250059350016 bytes, 488397168 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: dos
Disk identifier: 0x00000000

Device     Boot Start       End   Sectors   Size Id Type
/dev/sdc1  *        4 488397167 488397164 232.9G a5 FreeBSD

---

mycomp@mycomp ~ $ sudo mount -t vfat /dev/sdc1 /mnt/
mount: wrong fs type, bad option, bad superblock on /dev/sdc1,
missing codepage or helper program, or other error

In some cases useful info is found in syslog - try
dmesg | tail or so.

---

mycomp@mycomp ~ $ sudo mount -t ntfs /dev/sdc1 /mnt/
NTFS signature is missing.
Failed to mount '/dev/sdc1': Invalid argument
The device '/dev/sdc1' doesn't seem to have a valid NTFS.
Maybe the wrong device is used? Or the whole disk instead of a
partition (e.g. /dev/sda, not /dev/sda1)? Or the other way around?

---

mycomp@mycomp ~ $ sudo mount -o offset=2048 /dev/sdc1 /mnt/
mount: /dev/loop0 is write-protected, mounting read-only
NTFS signature is missing.
Failed to mount '/dev/loop0': Invalid argument
The device '/dev/loop0' doesn't seem to have a valid NTFS.
Maybe the wrong device is used? Or the whole disk instead of a
partition (e.g. /dev/sda, not /dev/sda1)? Or the other way around?

---

mycomp@mycomp ~ $ sudo ntfsfix /dev/sdc1
Mounting volume... NTFS signature is missing.
FAILED
Attempting to correct errors... NTFS signature is missing.
FAILED
Failed to startup volume: Invalid argument
NTFS signature is missing.
Trying the alternate boot sector
Unrecoverable error
Volume is corrupt. You should run chkdsk.

---

after the suggestion of acejavelin:

mycomp@mycomp ~ $ lsmod  | grep ufs
ufs                    73728  0 

---

mycomp@mycomp ~ $ sudo mount -t ufs -r -o ufstype=ufs2 /dev/sdc1 /mnt/
[sudo] password for mycomp: 
mount: wrong fs type, bad option, bad superblock on /dev/sdc1,
missing codepage or helper program, or other error

In some cases useful info is found in syslog - try
dmesg | tail or so.
          73728  0

---

mycomp@mycomp ~ $ dmesg | tail -1
[13211.885241] ufs: ufs_fill_super(): bad magic number

---

Afther suggestion of Andrea Lazzarotto:

testdisk analysis:

Disk /dev/sdc - 250 GB / 232 GiB - CHS 30401 255 63
Current partition structure:
Partition                  Start        End    Size in sectors

Invalid BSD disklabel
 1 * FreeBSD                  0   0  5 30401  80 63  488397164
 1 * FreeBSD                  0   0  5 30401  80 63  488397164

 Warning: Bad ending head (CHS and LBA don't match)

---

testdisk further analysis:

Disk /dev/sdc - 250 GB / 232 GiB - CHS 30401 255 63
Partition               Start        End    Size in sectors

No partition found or selected for recovery

---

Even more checks:

mycomp@mycomp ~ $ sudo file -s /dev/sdc
/dev/sdc: DOS/MBR boot sector

mycomp@mycomp ~ $ sudo file -s /dev/sdc1
/dev/sdc1: data

mycomp@mycomp ~ $ sudo mount -t msdos /dev/sdc /mnt
mount: wrong fs type, bad option, bad superblock on /dev/sdc, [...]

Been a while since I have done this with *BSD systems... but here goes.

According to your fdisk -l command, the partition's filesystem is "FreeBSD" which if correct is probably UFS, not fat, ntfs, or extX.

First, make sure you have the ufs module loaded with lsmod | grep ufs, if it is not listed, load the module with sudo modprobe ufs

Try to mount is a UFS filesystem

sudo mount -t ufs -r -o ufstype=ufs2 /dev/sdc1 /mnt/

Proceed as normal.